Micronesica 43(1): 51 – 100, 2012 The Endemic Plants of Micronesia: A Geographical Checklist and Commentary Craig M. Costion1 Australia Tropical Herbarium, JCU Cairns Campus, Cairns QLD 4870 Australia Centre for Evolutionary Biology & Biodiversity, University of Adelaide, Adelaide SA 5005 ccostion@googlemail.com David H. Lorence National Tropical Botanic Garden 3530 Papalina Road Kalaheo, Hawaii 96741 USA lorence@ntbg.org Abstract—The Micronesia-Polynesia bioregion is recognized as a global biodiversity hotspot. However, until now estimates regarding the number of endemic plant species for the region were not supported by any comprehensive published work for the region. The results of this study indicate that Micronesia has the world’s highest percentage of plant endemism per square kilometer out of all globally recognized insular biodiversity hotspots. A checklist of all endemic plant species for Micronesia is presented here with their corresponding geographical limits within the region. A summary of previous work and estimates is also provided noting the degree of taxonomic progress in the past several decades. A total of 364 vascular plant species are considered endemic to Micronesia, most of them being restricted to the Caroline Islands with a large percentage restricted to Palau. The checklist includes seven new combinations, one new name, and two unverified names that require additional study to verify endemic status. Overviews of each respective botanical family represented in the list are given including additional information on the Micronesian taxa. Recommendations for future work and potential projects are alluded to throughout the text highlighting major data gaps and very poorly known taxa. The following new combinations and names are made: Cyclosorus carolinensis (Hosokawa) Lorence, comb. nov., Cyclosorus gretheri (W. H. Wagner) Lorence, comb. nov., Cyclosorus guamensis (Holttum) Lorence, comb. nov., Cyclosorus palauensis (Hosokawa) Lorence, comb. nov., Cyclosorus rupiinsularis (Fosberg) Lorence, comb. nov., Dalbergia hosokawae Costion nom. nov., Syzygium trukensis (Hosokawa) Costion & E. Lucas comb. nov. 1 Author to whom which correspondence should be addressed 52 Micronesica 43(1), 2012 Introduction The word Micronesia, derived from Greek for “small islands,” is geographically apt. This bioregion spans a region of the Pacific Ocean comparable in size to the continental United States, or Australia, but the total land area of all the islands within this area sums to roughly 2,628 km². If all the islands of Micronesia were compressed into one land mass it would comfortably fit within the US state of Rhode Island. The sizes of the islands however, do not come even remotely close to reflecting the wealth of biodiversity they contain. The results of the present study indicate that Micronesia contains a higher percentage of endemic plant species per square kilometer land area than the Hawaiian archipelago by ten orders of magnitude. Despite this distinction, their remoteness has rendered them understudied and for the most part un-noticed. The paucity of studies in the region is compounded by its complex geology, having six distinct geological subregions of ages varying from up to 97 million years old in the Marshall Islands, the oldest coral islands and atolls on earth (Coppers 2009), to more recent volcanic events of < 1 million years old in the Northern Marianas (Trusdell 2009). The combination of old age and close proximity to continental land masses of some of the Micronesian islands has enabled them to accumulate a very high richness of distinct plant lineages compared to more remote archipelagos such as Hawaii. The available terrestrial habitat in Micronesia is literally packed with biodiversity, much of which is only known from a few collections. Micronesia, defined here as the Caroline, Mariana, Gilbert and Marshall Islands, (Fig. 1) is part of the Polynesia-Micronesia global biodiversity hot-spot (Conservation International 2007). These global biodiversity hotspots were determined primarily on the basis of the number of endemic plants contained within them and their degree of threat. Despite Micronesia’s noteworthy biodiversity and its long recognized importance for conservation, a complete checklist of endemic plants for the bioregion has been lacking until now. The present study aims to fill this gap by synthesizing all existing taxonomic literature to date for the region. All previous studies have relied entirely on estimates of the number of endemic plants for Micronesia. Estimates on quantity of endemic species may help address global priorities but the lack of a checklist of endemic plant species has prevented an assessment of species that are threatened and in need of priority for local conservation measures. Studies have shown that the Polynesia-Micronesia biodiversity hotspot is the most vulnerable of all the world’s biodiversity hotspots to extinctions due to its insular nature (Baillie et al. 2004), and thus such a list is far over-due. The present study draws primarily upon the extensive work of the eminent Pacific botanist Francis Raymond Fosberg (1908-1993) his collaborator Benjamin Stone (1933-1994), and the work of recent Pacific botanists. Fosberg provided a number of the endemic plants that occur in Micronesia in the abstracts of his geographical checklists (Fosberg et al 1979, 1981, 1987) but did not clearly indicate which taxa he considered endemic. All species listed in the checklists included their known distributions within Micronesia, yet confusion over whether these distributions were considered global or only the distributions of listed taxa within the Micronesia bioregion has abounded ever since. Fosberg’s estimates have been rou- Costion & Lorence: Endemic Plants of Micronesia Checklist 53 tinely utilized subsequently without further taxon specific and wider geographic verification. We can only speculate why Fosberg indicated that he knew how many endemics that occur in Micronesia but did not differentiate between true insular endemic taxa and species restricted to one archipelago in Micronesia but with wider representation elsewhere. This was done for the families covered in the Flora of Micronesia (Fosberg & Sachet 1975a, 1975b, 1977, 1980a) so it is likely that this task was saved for treatment in in the flora family by family where species concepts could be covered in greater depth. It is also possible that he hoped to inspire someone else to take on this substantial task. Whether or not the latter reason is true we cannot say, but we can say that this was the effect it had. The present study is the final product of an effort extending over seven years that began with the realization of this problem and fundamental gap in knowledge for Pacific botany. This “problem” however is old news for the Pacific. No less than 30 years ago, Benjamin Stone (1970) lamented in the introduction to his Flora of Guam that the production of a large volume such as a flora or checklist for a bioregion, often only the first stage of coming to grips with a flora and the biota it sustains, usually leads to the end of floristic research for that region. Though it can certainly be said that Fosberg and his collegues proved him wrong in this regard, there was perhaps a grain of truth in Stone’s statement. Aside from the baseline work of Fosberg and his collaborators much of the Micronesian flora remains very poorly studied and understood taxonomically. Many of the species Fosberg described have since become synonymized; others have yet to be verified, being known only from the type collection. Some of these have not even been collected since before WWII. Figure 1: Geographical boundaries of major island groups in the Micronesia region 54 Micronesica 43(1), 2012 Stone (1970) commented on this very slow process of taxonomic revision that over the course of decades, leads to new species concepts. This of course directly affects our understanding of what is and what isn’t endemic to a region. As Stone correctly predicted, several of Guam’s vascular plant species that he treated as endemic, 22% of the total, are no longer considered to be so. Our reassessment concludes that there are about 11 vascular plants endemic to Guam, including two pteridophytes and nine angiosperms. They are as follows: Ceratopteris gaudichaudii Brongniart, Cyclosorus guamensis (Holttum) Lorence, Dianella saffordiana Fosberg & Sachet, Bulbophyllum guamense Ames, Potamogeton marianensis Cham. & Schltdl., Eugenia bryanii Kaneh., Phyllanthus mariannensis W.L. Wagner & Lorence, Hedyotis megalantha Merr., Psychotria andersonii Fosberg, Psychotria malaspinae Merr., and Elatostema stenophyllum Merr.. Thus the long delay for the checklist presented here may have actually been fortuitous. Though we do expect this slow process to continue, (indeed from the time of submission of this manuscript to the time it reached the press two additional “endemics” from Palau, Maesa canfieldiae and Timonius salsedoi, have been found to be in need of revision along with others also suspected) we do feel that sufficient taxonomic progress has been made in the last two decades to warrant an authorative list. More importantly, we feel that from a conservation perspective this information is absolutely crucial for guiding policy and helping establish priorities for small island nations with limited resources and funding and that further delay could lead to more unnecessary extinctions in the already compromised Pacific biota. Although our checklist substantially reduces the number of endemic species that were estimated for Micronesia previously it in no way downlists Mirconesia as a globally important biodiversity hotspot. If anything, now residents in their respective islands will be better informed to prioritize local efforts and actions. Flagging such a huge bioregion as globally important can help raise international attention and funds, but applied conservation can only take place locally. This is especially true in Micronesia which spans millions of square miles of ocean and is divided into six nations or territories further split into at least ten major island state governments each with numerous regional tribal governments. We hope this checklist will serve to help do just that. To better enable this we have organized the checklist with the users in mind, avoiding jargon and technical terms wherever possible and providing a document that is well balanced between providing as much technical data as possible without losing the captive interest of readers by also including some more general facts and notes about plant identification, uses, and biogeography of the region. All species listed here are considered endemic to Micronesia or otherwise to island groups or single islands within Micronesia. We define endemic as a species that has a geographical range restricted to the region specified here. We classify species as endemic to Micronesia (occurs in the Carolines and Marianas), the Carolines (occurs on at least one island in both the Eastern and Western Carolines), the Marianas (occurs on the Southern and Northern Marianas), the Gilberts (excluding the other islands of the Republic of Kiribati), the Marshalls (endemic to the Republic of the Marshall Islands), the Southern Marianas (Guam, Rota, Tinian, and Costion & Lorence: Endemic Plants of Micronesia Checklist 55 Saipan), the Northern Marianas (all islands north of Saipan in the Commonwealth of the Northern Mariana Islands), the Western Carolines (occurs on the Palau and Yap archipelagos), the Eastern Carolines (occurs in more than one of the following island states: Chuuk, Pohnpei, and Kosrae), and finally species endemic to the island nations or states of Guam, Palau, Yap, Chuuk, Pohnpei, and Kosrae. In addition, when known, we have classified species that are restricted to specific soils within these categories. Species are either restricted to volcanic soils (V), limestone soils (L), have a generalist habit occuring on both (G), or are aquatic (A). We also list the growth forms of species to the best of our knowledge. Species are categorized as either one or two of the following growth forms: herb (H), epiphyte (E), herbaceous vine (HV), woody liana (WL), shrub (S), tree (T), canopy tree (T(c)), and understory tree (T(u)). Table 1: Soil type, growth form, and relative rarity index coding key Code Definition Soils Form Rarity Volcanic Limestone Generalist Aquatic Herb Epiphyte Herbaceous Vine Woody Liana Shrub Tree Canopy Tree Understory Tree Dominant Common Uncommon Rare Range Restricted V L G --------------- ---A H E HV WL S T T(c) T(u) ------ ------------D C U R RR A relative rarity index is provided based on a combined assement of our knowledge of the flora and review of the literature. We provide these data well aware that our knowledge of rarity is far from complete, and hope that the blanks in this or any of the other columns will inspire others to fill them in. In any case, for the species that we do know sufficiently, the relative rarity index can help identify immediate conservation priorities. We classify species as either one or a combination the following qualitative categories: Dominant (D) = Forms a dominant layer of at least one plant community in Micronesia Common (C) = Occurs frequently and throughout its known range Uncommon (U) = Occurs throughout its known range but not in abundance Rare (R) = Is very uncommon or has been rarely encountered, its range is not well known Range Restricted (RR) = Its distribution is known to be restricted to a very small area 56 Micronesica 43(1), 2012 The example below indicates that the species is a common liana or woody vine, is endemic to Yap, and is restricted to limestone soils. A complete key to the coding scheme is provided in Table 1. Taxon Name Genus species Author Endemic to Yap Soils L Form WL Rarity C The checklist is organized taxonomically following the most recent Angiosperm Phylogeny Group (APG) classification, subdivided into Gymnosperms, Pteridophytes, Basal Angiosperms, Monocots, and Eudicots. Families are then arranged in alphabetical order, followed by genera and species in alphabetical order. Below each family name we have listed in the following order the number of native genera/species(endemics) known from that family for Micronesia. A description is included for each family to briefly introduce the family and provide any other useful and or interesting information for specific taxa where deemed appropriate. Information on the number of species per family and genus was obtained from the Angiosperm Phylogeny Website (Stevens 2001) unless otherwise noted. We follow the classification of Smith et al. (2006) for the family concepts and species numbers of the Pteridophytes (ferns and lycophytes). Summary of Taxonomic Revision of Micronesia’s Endemic Flora A summary of revised percentages of Micronesia’s endemic flora is provided in the following table (Table 2). Changes of endemic status can be grouped into two categories; changes made due to revised species concepts and changes made due to herbarium records found outside Micronesia for particular taxa. To confirm endemic status we reviewed the literature for Micronesia. Primary resources included the checklists of Fosberg et al. (1979, 1981, 1987) and all of his subsequent publications, the Flora of Guam (Stone 1970), Flora Malesiana, the Kew’s World Checklist of Selected Plant Families (2010) online resource, and GrassBase (Clayton et al. 2002). Recent checklists have been published for Pohnpei (Lorence & Flynn 2009; Herrera et al. 2010). Another modern checklist exists for Palau (Hillman-Kitalong et al. 2008). We also scanned the the literature for family and generic level taxonomic revisions that applied to the Micronesian flora. Distribution records were scanned using additional online resources including the Global Biodiversity Information Facility (GBIF), herbarium records made available by request to the authors, or other reports and publications that cited distribution data. A complete list of species that were formerly considered endemic, such as in the Flora of Guam, with the accompanying citations or reasons for delisting is not provided here but is available upon request from the authors. If a species was listed in any of Fosberg’s publications or the Flora of Guam, we checked its endemic status, though we do apologize if anything has escaped our attention and welcome corrections, new records, and updated species concepts from other researchers. Endemic subspecies and varieties are not included in this list. We also excluded Costion & Lorence: Endemic Plants of Micronesia Checklist 57 phrase names or species only identified to genus level such as Oberonia sp. aff. podostachys Schltr. (Fosberg et al. 1987) to avoid falsely applying names of poorly understood or misidentified collections. Although we do expect new records and a few new species to be found in Micronesia, more cases of taxonomic revision over time are expected. This will lead to the incorporation of some currently recognized endemic species into broader species concepts and the opposite process of splitting widespread taxa into endemics with smaller distributions for others. This will require updating of our checklist periodically. Table 2: Summary of revised endemic species concepts for Micronesia No. of Endemics in Former Treatment No. of Endemics in Current Treatment Percent of Change Fosberg et al. (1979-1987) Dicots (369) Monocots (166) Pteridophytes (31) Gymnosperms (0) Total (566) Endemic to Micronesia Dicots (212) Monocots (121) Pteridophytes (30) Gymnosperms (1) Total (364) Total: 36% Guam (Stone 1970) Total (69) Endemic to Marianas Total (54) Total: 22% Palau (unpublished estimates) Total (200-260) Endemic to Palau Total (135) Total: 32-48% Dicots: 43% Monocots: 27% Pteridophytes: 3% Checklist of Endemic Species Taxon Name Endemic to Soils Form Rarity LYCOPHYTA (6) SELLAGINELLACEAE 1/7(6) Sellaginellaceae can be overlooked being small, uncommon herbs, often occurring along rocky stream banks or moist rocky outcroppings. They are related to the Lycopodiaceae and together form a distinct lineage that branched off before the radiation of ferns. One species occurs along edges of savannas in Palau. Selaginella kanehirae is known from Pohnpei and Kosrae, and S. volkensii is known from Yap and Chuuk. The rest are endemic to specific island states with the exception of S. ciliaris which is widespread in northern Australia and Southeast Asia. Currently, the relationships and species delimitations between the following taxa and the robustness of the species concepts are poorly understood and require further study. 58 Micronesica 43(1), 2012 Selaginella dorsicola Hosok. Selaginella kanehirae Alst. Selaginella kusaiensis Hosok. Selaginella palauensis Hosok. Selaginella pseudo-volkensii Hosok. Selaginella volkensii Hieron. Palau E. Carolines Kosrae Palau Palau Carolines V V V V V -- H H H H H H ------- PTERIDOPHYTA (24) CYATHEACEAE 1/3(2) There are three native tree fern species in Micronesia, formerly placed in Cyathea. Two of them are considered endemic. They are both locally abundant but Sphaeropteris aramaganensis is only known from three small islands in the N. Marianas on high volcanic slopes. S. nigricans occurs commonly in open savannas and in the forest understory of the Caroline Islands. S. lunulata is less common, but also occurs in Southeast Asia. Sphaeropteris aramaganensis (Kaneh) R. M. Tryon Sphaeropteris nigricans (Mett.) R. M. Tryon N. Marianas V T R Carolines V T C DRYOPTERIDACEAE 7/12(2) Dryopterdidaceae is a diverse family with over 1,700 species worldwide. Although they are cosmopolitan they are most abundant in temperate regions and the higher elevation mountain floras in the tropics. Elaphoglossum, Greek for serpent tongue, is mostly a tropical group with over 600 species. It was formerly placed in Lomariopsidaceae. Only two endemic species are known from Micronesia. One of these, E. kusaiense is possibly a synonym of E. carolinense. Elaphoglossum carolinense Hosok. Elaphoglossum kusaiense H. Ito E. Carolines Kosrae V V H H --- GLEICHENIACEAE 1/2(1) The Dicranopteris ferns of Micronesia are associated with open savannas, roadside banks, and other clearings. They form very dense thickets which are routinely burned by people to clear the way. This in turn prevents forest regeneration but also increases plant diversity in the savannas as it is hard for other plants to compete with Dicranopteris. Fosberg’s D. weatherbyi is distinguished from the Costion & Lorence: Endemic Plants of Micronesia Checklist 59 common D. linearis by its much larger overall size of all parts. It is known only from Pohnpei and Kosrae, and was listed as vulnerable on the 1997 IUCN Red List of Threatened Species. Carolines Dicranopteris weatherbyi (Fosberg) Glassman V H R LINDSAEACEAE 3/12(1) Lindsaeaceae is a small mostly tropical family with approximately 200 species. Its genera were formerly placed in Dennstaedtiaceae. Molecular data supports it as a monophyletic family and the most basal lineage in the Polypodiales. Tapeinidium is comprised of approximately 19 species, one of which, T. carolinense, is endemic to the Caroline Islands. Tapeinidium carolinense Kramer Carolines V H C LOMARIOPSIDACEAE 3/9(1) Lomariopsidaceae is almost entirely restricted to the tropics, with about 70 species. They are characterized by having dimorphic leaves where the fertile parts are on one leaf, the other sterile. Cyclopeltis is a small genus with only about seven described species. C. kingii is a very poorly known species restricted to the limestone forests of Palau. Cyclopeltis kingii (Hance) Hosok. Palau L H-E -- PTERIDACEAE 12/20(3) Pteridaceae, or the brake fern family, is a large fern family that has gone through much revision which is ongoing today. The family includes a number of genera that have been traditionally grouped into separate families. Relationships between genera remain unclear within the family which itself, as currently recognized, may not even be monophyletic. Adiantum, the maiden hair ferns, a genus of about 200 species, are distinctive in appearance and favored in horticulture. They are commonly associated with streambanks and rock faces adjacent to waterfalls. Ceratopteris was traditionally placed in the monotypic Parkeriaceae comprised of only four to six aquatic species. They are widespread in the tropics and comprise the only genus of homosporous ferns that is entirely aquatic. The status of C. gaudichaudii as an endemic variety or species is currently under investigation (Masuyama & Adjie 2008). The genus Pteris has approximately 280 species worldwide with one Micronesian endemic represented by only a few collections. The name Pteris is derived from the Greek word for fern. 60 Micronesica 43(1), 2012 Adiantum palaoense C. Chr. Palau Ceratopteris gaudichaudii Brongniart Guam Pteris tapeinidiifolia H. Itô Palau V A L H H H-E ---- POLYPODIACEAE 14/20(5) Polypodiaceae has over 1,500 species, mostly tropical and epiphytic. Several traditional families have been incorporated into this larger circumscription of Polypodiaceae. About 20 species have been recorded from the Micronesian region. All four genera listed below were formerly placed in Grammitidaceae. Calymmodon is mostly an Indomalaysian genus of 25-30 species. Grammitis formerly contained about 200 species. Most of these have been transferred to other genera including Ctenopterella, Oreogrammitis, and Prosaptia, leaving Grammitis with about 25 species. Grammitis ponapensis will very likely be separated into a new genus that has yet to be described. Prosaptia contains approximately 50 species with Indomalaysian-Pacific distribution. Its name in Greek refers to its distinctive sori, “immersed or inserted” in the lamina. Calymmodon ponapensis Copel. Oreogrammitis palauensis (Hosok.) Parris Grammitis ponapensis Copel. Oreogrammitis scleroglossoides (Copel.) Parris Prosaptia palauensis Hosok. Pohnpei Palau V V E E --- Pohnpei Pohnpei V V E E --- Palau V H -- THELYPTERIDACEAE 3/19(8) Thelypteridaceae is a large, mostly tropical family with approximately 950 species. Most are terrestrial; a few are lithophytic or semi-aquatic. The taxonomy of this family has been problematic with no consensus on the correct circumscription of genera. Traditionally Micronesia’s species have either been treated all under Thelypteris (Fosberg et al. 1982) or split into several separate genera (Holttum 1977). We follow the circumscription of Thelypteridaceae genera presented by Smith et al. (2006), and treat all of the Micronesian endemics under Cyclosorus. Cyclosorus carolinensis (Hosokawa) Lorence Cyclosorus perglanduliferus (Alderw.) Ching Cyclosorus gretheri (W. H. Wagner) Lorence Cyclosorus guamensis (Holttum) Lorence Palau L H -- Palau V H -- S. Marianas L H C Guam -- H -- Costion & Lorence: Endemic Plants of Micronesia Checklist Cyclosorus maemonensis Wagner & Grether Cyclosorus palauensis (Hosokawa) Lorence Cyclosorus ponapeanus (Hosokawa) Lorence Cyclosorus rupicola (Hosokawa) Lorence 61 Micronesia -- H U W. Carolines V H -- Pohnpei V H -- Palau L H -- WOODSIACEAE 1/6(1) Woodsiaceae contains approximately 700 species circumscribed into 15 genera. Most species are placed within two genera including Diplazium. Diplazium contains approximately 400 species, though is likely a paraphyletic genus (Smith 2006). Its name is derived from the Greek diplazios, meaning double, referring to the indusia that lie on both sides of the lamina veins. Diplazium ponapense (Copel.) Hosok. may be synonymous with the older name D. melanocaulon Brack. Diplazium ponapense (Copel.) Hosok. E. Carolines V H -- GYMNOSPERMAE (1) CYCADACEAE 1/2(1) There are two native cycad species in Micronesia. One is considered endemic (Hill 1994; 2004), the other also occurs in Southeast Asia (DeLaubenfels 2007). These two species were formerly treated as one widespread species, Cycas circinalis, which is now regarded as endemic to the Western Ghats of India (Hill 2004). A more complete discussion on the history of this taxonomic problem was covered by Costion (2009). The local distribution of the two separate species that occur in Palau is not well known as they were formerly treated as one species. They can occur on all soil types but are more commonly found on sandy beach forest and on limestone islands. In the Marianas and to a lesser extent in the Rock Islands of Palau, C. micronesica can be abundant enough to form dense understory stands. Flour made from the seeds was often eaten by the indigenous Chamoro of Guam until it was suspected to be linked with the degenerative neurological disease known as Guam dementia. Henceforth, consuming the seeds has been discouraged. However, the exact causes of the disease are to date, unresolved. Cycas micronesica K.D. Hill Micronesia G T-S C-R 62 Micronesica 43(1), 2012 BASAL ANGIOSPERMS (15) ANNONACEAE 3/3(3) Guamia was previously considered the only angiosperm genus endemic to Micronesia. Schatz (1987) revised this by describing a new species of Guamia, G. mexicana, from Mexico. The Guam species, however, is retained as an endemic species. It occurs abundantly on limestone soils in the Marianas, and occasionally on mixed soils. Both Annonaceae species from Palau are very poorly known and likely quite rare. Polyalthia merrillii may be only known from the type. Goniothalamus carolinensis is only known from the island of Babeldoab from a few collections. Notes from herbarium collections indicate that even the early Japanese collectors regarded it as a rare and uncommon tree. Goniothalamus carolinensis Kaneh. Guamia mariannae (Safford) Merrill Polyalthia merrillii Kaneh. Palau Marianas Palau V G L T T T R A -- LAURACEAE 2/4(2) Cinnamomum is a pantropical genus with approximately 250 species distributed throughout the Neotropics, Pacific, and Australasia. Cinnamomum and other members of this family are regarded as characteristic components of neotropical montane cloud forest canopy. Micronesia is notably home to the lowest elevation cloud forests in the world, occurring on the islands of Pohnpei and Kosrae. Both Micronesian species of Cinnamomum occur on Pohnpei. Cinnamomum carolinense is also known from Kosrae and Palau, but in Palau it is rare. On the island of Pohnpei, the leaves of native Cinnamomum species are boiled to make a delicious tea that has reported medicinal qualities. The only other native Lauraceae in the region belongs to Cassytha, a parasitic group of plants mostly of Australian distribution. Cassytha filiformis is a cosmopolitan species which commonly occurs in the savannas and coastal areas of Micronesia. Cinnamomum sessilifolium Kaneh. Cinnamomum carolinense Koidz. Pohnpei Carolines V V T T --- MYRISTICACEAE 2/3(1) Myristicaceae is a pantropical family, though only a few species occur in Australia and the Pacific. Horsfieldia is represented by approximately 100 species, mostly in SE Asia with one species in Australia and a few species extending east to Micronesia and the Solomon Islands. H. palauensis is a common and characteristic Costion & Lorence: Endemic Plants of Micronesia Checklist 63 component of Palau’s volcanic upland and limestone forests. The widespread H. irya reaches its north eastern limit of distribution in Palau and Kosrae where it was formerly treated as the endemics H. amklaal and H. nunu. It is associated with fresh water and in Palau forms impressive stands of swamp forest in association with two Calophyllum species. Horsfieldia tuberculata was recorded for Palau under the previous name H. novo-guineensis; however it is very poorly known and rarely collected there. Local residents cannot distinguish it from the other two and some doubt it as a valid record. Myristica insularis was formerly regarded as endemic to the Carolines but was revised to be a variety M. hypargraea, a species also known from Samoa and Tonga, by de Wilde (1994). The author admittedly reported that limited material was studied ex situ and acknowledged morphological differences in the fruit and leaves but that the two were close enough to merit merging the taxa. Molecular studies may indicate otherwise and revive the endemic name. Horsfieldia palauensis Kaneh. Palau G T C PIPERACEAE 2/15(9) Piperaceae are well represented and rich in endemics in Micronesia. Some species are well known while others are not and require further study (Fosberg & Sachet 1975). Both Peperomia and Piper are pantropical in distribution. Peperomia usually occurs as a terrestrial, epiphytic or lithophytic herb, while Piper often occurs as a shrub or hemiepiphytic vine. In Peperomia, P. breviramula occurs in the montane forest of Pohnpei and is known only from the type and one other collection. It is potentially the same species as P. glassmanii which is also endemic to the Pohnpei mountain flora. Peperomia kusaiensis is epiphytic in the cloud forests of Kosrae, and P. ponapensis is lithophytic on limestone and basalt at low elevations in the Eastern Carolines from Chuk to the Marshall Islands. Piper is an important native plant genus for the people of Micronesia. Piper betle and P. methysticum are both used in the preparation of local intoxicants. Though the latter is only exploited in Pohnpei, the former is inseparable from daily life throughout Micronesia. Piper nigrum, black pepper, though introduced, has historical significance in the region where it was at one time a valuable commercial crop. Two species of Piper are endemic to Micronesia. Peperomia breviramula C.DC. Peperomia glassmanii Yunck. Peperomia kraemeri C.DC. Peperomia kusaiensis Hosok. Peperomia mariannensis C.DC. Peperomia palauensis C.DC. Peperomia ponapensis C.DC. Piper guahamense C.DC Piper hosokawae Fosberg Pohnpei Pohnpei Palau Kosrae Marianas Palau Micronesia Marianas Palau V V G V L G G L G E E H E H H H S WL R ----C -C C 64 Micronesica 43(1), 2012 MONOCOTS (121) ARACEAE 6/9(2) The arum or aroid family is mostly tropical and known for the calcium oxalate crystals or raphides present in most species. This explains the necessary preparations required for eating the main staple of most of Micronesia and Polynesia. Taro, a member of this family cultivated for its carbohydrate and nutrient-rich corms, has numerous varieties spanning four genera and several species. Many of these were introduced into the Pacific from Southeast Asia. Micronesia has two endemic aroids that occur as climbing vines. Epipremnum carolinense Volkens Scindapsus carolinensis Hosok. W. Carolines Chuuk V -- H-E H-E C -- ARECACEAE 8/11(7) Micronesia is home to eleven native palm species, seven of them endemic. Several of these palms have undergone recent name changes. Ponapea is a genus of only three known species, all endemic to Micronesia. It was formerly partially included under Ptychosperma. All three species of Ponapea are rare with the exception of P. ledermanniana which is common on Kosrae, though it is threatened and in decline on Pohnpei (Lewis 2008). Ponapea hosinoi has a very small natural range on Pohnpei making it highly vulnerable to habitat loss. Ponapea palauensis is considered Critically Endangered under IUCN red listing criteria (Costion et al. 2009) due to its very small extent of occurrence. Clinostigma is a genus of 11 species endemic to the south and western Pacific. One species, C. ponapense, is endemic to Pohnpei where it is abundant in some localities, while the other, C. carolinense, is endemic to Chuuk. The genus Hydriastele was recently revised to incorporate three other genera including Gulubia. Its range now stretches from New Zealand to Indonesia and the Pacific with most species occurring in New Guinea. The Palau species is found in patches scattered throughout the Rock Islands. Metroxylon is the sago palm genus, widely utilized for the starch extracted from the pith. There are seven species total, the Micronesian species being the only species that is not monocarpic (flowers only once then dies). Clinostigma carolinense (Becc.) Moore & Fosberg Clinostigma ponapense (Becc.) Moore & Fosberg Hydriastele palauensis (Becc.) W.J.Baker & Loo Chuuk -- -- -- Pohnpei V T -- Palau L T U-R Costion & Lorence: Endemic Plants of Micronesia Checklist Metroxylon amicarum (H.Wendl.) Hook.f. Ponapea hosinoi Kaneh. Ponapea ledermanniana Becc. Ponapea palauensis Kaneh. 65 Micronesia -- T -- Pohnpei E. Carolines Palau V V L T T T --R CYPERACEAE 13/64(4) There are over 4,000 species of sedges found worldwide. They are most abundant in the tropics and most commonly associated with wetland or riparian areas and poor soils. They are well represented in Micronesia where there is no shortage of poor soils and wet areas. Four species are considered endemic. Hypolytrum dissitiflorum Steud. Hypolytrum flavinux (T. Koyama) D.A. Simpson Fimbristylis palauensis Ohwi Mapania pacifica (Hosok.) T. Koyama E. Carolines Palau -V H H --- Palau E. Carolines V V H H --- HEMEROCALLIDACEAE 1/2(2) This family has tentatively been placed within the Xanthorrhoeaceae as a subfamily along with Asphlodaceae by some authors. Since morphological support for this view is lacking and molecular data remain inconclusive we retain it as a distinct family following Mabberley (2008). Xanthorrhoeaceae sensu stricto are the characteristic “grass trees” endemic to Australia forming a monotypic family of approximately 28 species. Hemerocallidaceae has approximately 63-85 species distributed on all continents except North America. Dianella has about 40 known species, many of which are endemic to Australia. The two Micronesian species commonly occur in open savannas or barren volcanic soils. They have attractive blue to purplish flowers and fruits making them good native ornamental candidates. Dianella carolinensis Laut. W. Carolines Dianella saffordiana Fosberg & Sachet Guam V V H H C C ORCHIDACEAE 50/120(85) The orchids form the largest angiosperm family with over 22,000 species worldwide. It is the most diverse family in Micronesia for both native and endemic species and also one of the most likely Micronesian plant groups to have new species yet to be discovered. There is a long list of potential new orchid species from Micronesia. These tentative names are not included here as most are unverified records or 66 Micronesica 43(1), 2012 based on infertile specimens. The three largest orchid genera in Micronesia are Bulbophyllum (6), Phreatia (7), and Dendrobium (12). Bulbophyllum is the largest orchid genus and with over 1,800 species is one of the largest plant genera in the world. Its centre of diversity is New Guinea. Phreatia is a small genus of about 150 mostly Indomalesian species. Some were formerly placed in Rhynchophreatia, which is no longer an accepted genus. Dendrobium is also a large genus found from Asia to the Pacific. All are either epiphytes or lithophytes. Most of Micronesia’s orchids have small inconspicuous flowers, though a few such as Dendrobium palawense, Dendrobium mirbelianum, and Dipodium freycinetioides have much horticultural potential and are already being harvested in alarming quantities from the forests for local gardens. Aglossorrhyncha micronesiaca Schltr. Agrostophyllum kusaiense Tuyama Agrostophyllum palawense Schltr. Bulbophyllum desmanthum Tuyama Bulbophyllum fukuyamae Tuyama Bulbophyllum guamense Ames Bulbophyllum hatusimanum Tuyama Bulbophyllum kusaiense Tuyama Bulbophyllum micronesiacum Schltr. Cherostylis raymundii Schltr. Chiloschista loheri Schltr. Cleisostoma porrigens (Fukuy.) Garay Coelogyne guamensis Ames. Corybas ponapensis Hosok. & Fukuy. Crepidium calcarea (Schltr.) D. L. Szlachetko Crepidium kerstingiana (Schltr.) D.L. Szlachetko Crepidium palawensis (Schltr.) D. L. Szlachetko Crepidium setipes (Schltr.) D. L. Szlachetko Cystorchis ogurae (Tuyama) Ormerod & P. J. Cribb Dendrobium adamsii A. D. Hawkes Dendrobium brachyanthum Schltr. Dendrobium carolinense Schltr. Dendrobium guamense Ames. Dendrobium implicatum Fukuy. Dendrobium kerstingianum Schltr. Dendrobium kraemeri Schltr. Dendrobium oblongimentum Hosok. & Fukuy. Palau Kosrae Palau Palau Kosrae Guam Palau Kosrae Micronesia W. Carolines Palau Palau Micronesia Pohnpei Palau V V V V V -V V V -G V V V L E E E E E E E E E H E E H-E E H ---------R C U -R -- Palau G H U Palau V H U Palau V H A Palau V H -- Pohnpei Palau E. Carolines S. Marianas Palau Palau Carolines S. Marianas V V V -V V G -- E E E E E E E E -C C ------ Costion & Lorence: Endemic Plants of Micronesia Checklist Dendrobium okabeanum Tuyama Dendrobium palawense Schltr. Dendrobium patentifiliforme Hosok. Dendrobium ponapense Schltr. Didymoplexis trukensis Tuyama Dienia volkensi M.A. Clem. & D.L. Jones Diplocaulobium carolinense A. D. Hawkes Diplocaulobium elongaticolle (Schltr.) Hawkes Diplocaulobium flavicolle (Schltr.) Hawkes Dipodium freycinetioides Fukuy. Glomera carolinensis L. O. Williams Liparis dolichostachya Fukuy. Liparis palawensis Tuyama Liparis yamadae (Tuyama) Fosberg & Sachet Malaxis alamaganensis S. Kobay. Malaxis trukensis (Fukuy.) Fosberg & Sachet Micropera draco (Tuyama) P.J. Cribb & Ormerod Microtatorchis hosokawae Fukuy. Moerenhoutia hosokawae (Fukuy.) Tuyama Moerenhoutia laxa Schltr. Moerenhoutia leucantha Schltr. Nervilia jacksoniae Rinehart & Fosberg Nervilia palawensis Schltr. Nervilia trichophylla Fukuy. Oberonia hosokawae Fukuy. Oberonia palawensis Schltr. Oberonia ponapensis Tuyama Oberonia rotunda Hosok. Peristylus carolinensis (Schltr.) Tuyama Peristylus palawensis (Tuyama) Tuyama Peristylus setifera Tuyama Phreatia carolinensis Schltr. Phreatia kanehirae Fukuy. Phreatia kusaiensis Tuyama 67 Chuuk Palau Palau E. Carolines Chuuk W. Carolines -L V --V E E E E H H ------- Pohnpei V E -- W. Carolines G E C Pohnpei V E -- Palau Pohnpei Palau Palau Palau V V V V V E E H-E H-E H-E ------ N. Marianas Chuuk V -- H H R -- Palau V E -- Pohnpei Carolines V V E H --- Palau Ponhpei Marianas V V -- H H H U --- W. Carolines Palau Ponhpei Palau Pohnpei W. Carolines Pohnpei G V V G V V V H H E E E E H R R ------ Palau V H R W. Carolines Pohnpei Palau Kosrae V V V V H E E E R ---- 68 Micronesica 43(1), 2012 Phreatia palawensis (Schltr.) Tuayama Phreatia ponapensis Schltr. Phreatia pseudothompsonii Tuyama Phreatia thompsonii Ames Pseuderia micronesiaca Schltr. Pseudovanilla ponapensis (Kaneh. & Yam.) Garay Rhynchophreatia pacifica Fukuy. Robiquetia kusaiensis Fukuy. Robiquetia lutea (Volk.) Schltr. Robiquetia palawensis Tuyama Robiquetia trukensis Tuyama Spathoglottis carolinensis Schltr. Spathoglottis micronesiaca Schltr. Taeniophyllum marianense Schltr. Taeniophyllum palawense Schltr. Taeniophyllum petrophilum Schltr. Taeniophyllum trukense Fukuy. Thrixspermum arachnitiforme Schltr. Thrixspermum ponapense Tuyama Trichoglottis ledermannii Schltr. Vrydagzynea micronesiaca Schltr. Zeuxine fritzii Schltr. Zeuxine ovata (Gaudich.) Garay. & W. Kittr. Zeuxine palawensis Tuyama Palau Pohnpei Ponhpei Micronesia Carolines Pohnpei L V V -V V E E E E E E-V -----U Kosrae Kosrae Carolines Palau Chuuk W. Carolines W. Carolines Carolines Palau Carolines Chuuk Ponhpei Pohnpei Carolines Carolines Micronesia Marianas V V -G V V V -V --V V G V --- E E E E E H H E E E E E E E H H H ------------------ Palau V H C PANDANACEAE 2/17(12) Pandanaceae, the screwpine family, is a large Old World family of over 800 species ocurring from tropical Africa and Madagascar to the Pacific. Freycinetia is a genus of woody climbers. They are easy to distinguish in a dense forest canopy by their trifarious spiralled leaves. Micronesia has three species, two of which are endemic. The third, F. reineckei, also occurrs in Samoa. Pandanus is a large genus which has been subject to considerable taxonomic dispute in the Pacific due to some species such as P. tectorius having variable forms from island to island. These plants do well along the coast and in poor soils but seem to occur in just about every habitat in Micronesia from the fire adapted P. tectorius association in the savannas to the salt tolerant P. kanehirae swamp forest association of Palau. They also range considerably in size from the enormous P. dubius to small understory trees such as P. amiriikensis, and even potentially small scandent shrubs as observed for the elusive P. peiliuensis. All parts of the plants are widely utilized by Micronesians for food, basketry, mats, clothing, medicine, fishing tools, and even sails. Costion & Lorence: Endemic Plants of Micronesia Checklist Freycinetia ponapensis Martelli Freycinetia villalobosii Martelli Pandanus aimiriikensis Martelli Pandanus amissus Huynh Pandanus japensis Martelli Pandanus kanehirae Martelli Pandanus kusaicolus Kaneh. Pandanus lorencei Huynh Pandanus macrojeanneretia Martelli Pandanus palawensis Martelli Pandanus patina Martelli Pandanus peliliuensis Kaneh. E. Carolines Palau Palau Kosrae Yap Palau Kosrae Palau Palau Palau Pohnpei Palau V V V V -V V L V V V L 69 WL WL T(u) T T T T T T T T-S T-S -C-A C-A U -U U -U --R POACEAE 46/90(7) The grass family is one of the few angiosperm families that is literally global in distribution. Over 10,000 species of grasses are found from the arctic to sub-Saharan Africa and into the Pacific, and the family is subdivided into 13 subfamilies and over 650 genera. The adaptability and evolutionary capacity of grasses is evident even in Micronesia’s Gilbert Islands. Lepturus pilgerianus is the only endemic plant species that occurs on these small atolls dominant with the characteristic Pacific atoll vegetation. Despite the reputation of many grass species as weeds, including species in the genera Digitaria, Isachne, Ischaemum, Panicum, and Sporobolus, there are also both native and endemic species in Micronesia. The grasses are one of the most important plant families to human society, having given rise to most major cereal crops. They were not exploited for food by the islanders of Micronesia in the pre-European contact era, though today rice is a common staple and in many islands has almost entirely replaced traditional staples. Digitaria gaudichaudii (Kunth) Henrard Digitaria mezii Kaneh. Isachne carolinensis Ohwi Ischaemum longisetum Merrill Lepturus pilgerianus Hans. & Potzt. Panicum palauense Ohwi Sporobolus farinosus Hosok. Marianas -- H -- Marianas Pohnpei Marianas Gilbert Is. Palau Micronesia -V L L V L? H H H H H H ------- POTAMOGETONACEAE 2/3(1) The pondweed family is comprised of about 120 species worldwide. They are all aquatic perennial herbs with tetramerous flowers lacking petals. Many species are regarded as having vitally important roles in their ecosystems by providing habitat 70 Micronesica 43(1), 2012 and food for other organisms, notably ducks. The Marianas endemic Potamogeton species may have been a food plant for the Marianas mallard (Stone 1970), Anas oustaleti, which was declared extinct in 1981 after several decades of decline from loss of wetland habitat. Guam Potamogeton marianensis Cham. & Schltdl. A H -- ZINGIBERACEAE 4/6(1) Alpinia is the largest and most widespread genus in the ginger family. It has approximately 230 species distributed in the Asia-Pacific region, though recent studies indicate that it is a polyphyletic genus (Kress et al. 2005). Alpinia carolinensis belongs to subgenus Dieramalpinia (Smith 1990), which is comprised of taxa occurring mostly east of Wallace’s Line. Many species of Alpinia are popular as ornamentals. Micronesia’s endemic, “giant ginger” has for the most part, not been exploited in this regard though many plant enthusiasts express utter amazement at its size. It is one of the largest species in the entire ginger family, reaching up to 8 meters (26 feet) tall. It is a common component of the forest understory on the volcanic islands. Alpinia carolinensis Koidz. Carolines V H/T C EUDICOTS (195) ACANTHACEAE 5/8(3) Acanthaceae is a mostly tropical family of about 4,000 species. They are often easily identified by their opposite leaves with swollen nodes and showy petalaoid bracts, but not all species display these characters. There are three native and one endemic Hemigraphis species in Micronesia, occurring as small herbs. The endemic H. pacifica is poorly known, though has been observed and collected along the stream banks of Babeldaob. It has been confused with H. palauana which Fosberg et al. (1979) treat as a synonym for H. angustifolia, native to Palau. Pseuderanthemum has several ornamental species that are widely cultivated and popular in Micronesia. Fosberg and Sachet (1980) described an additional endemic Pseuderanthemum distinct from P. inclusum by its leaf and inflorescence shape, longer floral parts, and warty seeds. Hemigraphis pacifica Hosok. Pseuderanthemum inclusum Hosok. Pseuderanthemum palauense Fosberg & Sachet Palau Palau Palau V V G H H H ---- Costion & Lorence: Endemic Plants of Micronesia Checklist 71 ANACARDIACEAE 5/7(4) The Anacardiaceae family has about 600 species with its center of diversity in Malesia. The family contains the well known cash crops mango, cashew, and the poison ivy of North America. Members of this family contain highly poisonous sap that often turns black and is caustic, causing minor to severe skin irritations. A liberal dose of Semecarpus sap in particular can lead to hospitalization. Micronesians take care when entering the forest, especially after rain, and avoid this plant entirely. The fruits are subtended by a fleshy receptacle which is allegedly edible. The genus has about 60 species, mostly in Southeast Asia. Buchanania is a small genus of roughly 25 tree species from Asia to the Pacific. The two endemics from the Western Carolines are difficult to distinguish and have been confused in Palau. Buchanania engleriana Volk. Buchanania palawensis Lauterb. Semecarpus kraemeri Lauterb. Semecarpus venenosus Volk. W. Carolines Palau Chuuk W. Carolines ---G T T T T C U -C APOCYNACEAE 14/21(7) The Apocynaceae family now incorporates the former family Asclepiadaceae as a subfamily. Asclepiadaceae was split from Apocynaceae in the 1800’s primarily on the basis of the presence of pollinia. A pollinium is a sac of pollen grains that is dispersed by sticking to an insect as it visits the flower for nectar. Orchids have also independently evolved this unique pollination strategy. Molecular data now show that Asclepiadaceae is not monophyletic and is nested within Apocynaceae. The family is easy to identify by its milky white latex, opposite or whorled leaves, and often two-parted fruits. The latex is often highly toxic and for some species it is known to cause temporary to permanent blindness. Thus care should be taken when handling the plants. Rauvolfia, a genus of about 110 mostly tropical trees and shrubs, is of interest for research in medicinal plants. Several members of this genus are rich in biochemical compounds that have been used in medicine, notably R. serpentina, which has been used to treat snake bites and wounds for millennia and more recently as the source of reserpine, an antihypertensive drug and tranquilizer. Hoya schneei Schltr. Hoya trukensis Hosok. Lepinia ponapensis Hosok. Lepiniopsis trilocularis Mgf. Melodinus insularis (Markgr.) Fosberg Ochrosia mariannensis A.DC. Rauvolfia insularis Markgr. Pohnpei Chuuk Pohnpei Carolines Palau Marianas Palau V -V L V G V HV HV T T-S WL T T --RR --C U,RR 72 Micronesica 43(1), 2012 APTANDRACEAE 1/1(1) Aptandraceae is a very small family of parasitic plants. There are only 34 species but these are subdivided into eight different genera. Anacalosa was formerly placed in the Olacaceae family. Anacalosa is a pantropical genus with about 18 species. The plants are dioecious with leaves two-ranked on zig-zag shaped branches. Anacalosa glochidiiformis is a small tree with small white flowers and orange fruits. The members of this family are suspected to be root parasites; however, direct evidence of functional haustoria, the roots that penetrate the host’s tissue to extract nutrients, has yet to be recorded. Anacalosa glochidiiformis Kaneh. & Hatus. Palau G T U AQUIFOLIACEAE 1/1(1) The genus Ilex, comprises the entire montypic Aquifoliaceae family, commonly known as the hollies. There are over 400 species found worldwide. The genus is most diverse in the tropics but also extends into temperate regions. Many are endemic to mountain ranges in the temperate tropical montane flora, but species also occur in the humid lowlands and on oceanic islands. Ilex volkensiana is found only in the cloud forests of Pohnpei. Ilex volkensiana (Loes.) Kaneh. & Hatus. Pohnpei V T -- ARALIACEAE 3/9(8) The Araliaceae or ginseng family is a mostly tropical family occurring worldwide. Osmoxylon has approximately 60 species, mostly concentrated in east Malesia, the Philippines, and Melanesia. Its Pacific distribution is limited to the Solomon Islands, Vanuatu, and Micronesia. Osmoxylon oliveri is a common understory component throughout Palau, whereas O. pachyphyllum is less common but widespread, and O. truncatum is only known from a few collections. It is considered endemic to southern Babeldaob. Osmoxylon mariannense is endemic to Rota. Polyscias is a genus of small to medium sized understory trees in the tropics with roughly 130 species. Molecular work (Plunkett et al. 2001) suggests the genus is paraphyletic with at least four to five distinct clades represented in the Pacific. Schefflera is a polyphyletic genus of over 600 species, also with 5 separate geographically distinct clades (Plunkett 2005). Micronesia’s native S. elliptica belongs to the Asian clade. However the Chuuk endemic S. kraemeri has not been included in any molecular phylogenies to date. This is worth noting considering a separate Costion & Lorence: Endemic Plants of Micronesia Checklist 73 Pacifc clade of Schefflera is recognized with its center of diversity in Melanesia. Thus, Micronesia’s Schefflera and Polyscias species could potentially be derived from more than one dispersal event within each genus. The Melanesian-centered clade of Schefflera is sister to Meryta. Meryta is a genus of approximately 30 species endemic to the South Pacific, all restricted to islands or island groups from New Caledonia to the Marquesas (Tronchet 2005). Osmoxylon mariannense Fosberg & Sachet Osmoxylon oliveri Fosberg & Sachet Osmoxylon pachyphyllum Fosberg & Sachet Osmoxylon truncatum (Kaneh.) Fosberg & Sachet Meryta senfftiana Volkens Polyscias grandifolia Volkens Polyscias subcapitata Kaneh. Schefflera kraemeri Harms S. Marianas -- T -- Palau Palau G G T(u) T(u) A U Palau V T(u) -- Micronesia Micronesia Kosrae Chuuk -L V -- T T(u) T -- C C --- BORAGINACEAE 4/8(1) Cordia is a pantropical genus with over 200 species worldwide. Its center of diversity is in the West Indies. The borage family is famous in botany for the Echium species of the Canary Islands that show an insular shift to woodiness from an herbaceous lineage. The borage family has adapted well to insular life and is represented in Pacific atoll vegetation with widespread Heliotropium, Cordia, and Tournefortia species. Cordia micronesica is likely derived from the widespread palaeotropic species C. subcordata, characteristic of strand vegetation. Both its flowers and fruits are substantially smaller than the latter, however, and its leaves are more distinctly serrated. Cordia subcordata is revered by islanders for its lightweight durable wood but also has many other uses including dye and medicine. Cordia micronesica Kaneh. & Hatus. Palau V T U-R CAPPARACEAE 2/3(1) The relatively small caper family is closely related to Brassicaceae, the mustard family. Capparis has about 250 species worldwide of mostly shrubs or lianas and is famous for the pickled condiments capers. Capparis carolinensis occurs on the limestone islands of Palau. It was treated as a synonym by Jacobs (1960) but was confused with its relative and putative ancestor, C. cordifolia. Capparis carolinensis has larger, more elliptic leaves compared to C. cordifolia’s distinct orbicular leaves and has smaller, more numerous, clustered flower buds. Capparis cordifolia has 74 Micronesica 43(1), 2012 a more widespread distribution in the Pacific but in Micronesia occurs only on Palau’s limestone islands. Capparis carolinensis Kaneh. Palau L S -- CELASTRACEAE 3/5(2) The Celastraceae family has approximately 1,350 species worldwide and now incorporates the former Hippocrateaceae. They most commonly occur as small trees, shrubs, or lianas, but there are two herbaceous genera. They are often characterized by the distinctive nectar disk present in the flowers. In most species, the flowers are yellow to greenish and inconspicuous. The family as a whole is not very economically important, though a few species are used as ornamentals in the genera Celastrus and Euonymus, and a narcotic is derived from Catha edulis, a native of East Africa and Arabia. Maytenus is a pantropical genus with 200-270 species. Both of Micronesia’s endemics are relatively common where they occur. Maytenus palauica (Loes.) Fosberg Palau Maytenus thompsonii (Merr.) Fosberg S. Marianas G L S S C C CLUSIACEAE 4/10(7) The Clusiaceae (or Guttiferae) is a small family of about 600 species mostly restricted to the moist tropics. Members of this family have opposite leaves and usually have latex that can be creamy to off white or bright yellow to orange in color. Garcinia is the mangosteen genus, named after the esteemed fruit from Southeast Asia, G. mangostana. Several other species are also cultivated for their fruits, and others have medicinal compounds that are utilized in traditional and modern medicine. Garcinia now includes the genus Pentaphalangium, which was formerly applied to G. carolinensis and G. volkensii. The genus Calophyllum is well known in the Pacific from the widespread strand tree Calophyllum inophyllum. This has evolved into a separate variety, C. inophyllum var. wakamatsui, found inland from the coasts on the volcanic island of Babeldaob where it can reach impressive sizes along ridgelines. Palau’s other endemic, C. pelewense, is probably derived from C. soulattri, which is very similar in morphology. Calophyllum soulattri is also widespread in distribution from Vietnam to Australia. Kayea is a smaller genus of about 65 species from India to Australia. The Palau endemic is an uncommon riparian tree with foliage resembling Cynometra ramiflora, and thus the same vernacular name is somtimes applied to both. Calophyllum pelewense P.F. Stevens Palau Garcinia carolinensis (Ltb.) Kosterm. Chuuk Garcinia matsudai Kaneh. Palau V -V T(c) T T U -C-A Costion & Lorence: Endemic Plants of Micronesia Checklist Garcinia ponapensis Laut. Garcinia rumiyo Kaneh. Garcinia volkensii (Ltb.) Kosterm. Kayea pacifica Hosok. E. Carolines W. Carolines Yap Palau V --V 75 T T T T ---U COMBRETACEAE 3/7(3) The Combretaceae family consists of about 500 species of trees or lianas mostly in the tropics. Species of Terminalia are generally large trees with a characteristic “pagoda- like” branching pattern and leaves clustered at the twig tips in rosettes. Its name is derived from the Latin terminus, referring to the terminal foliage and branching pattern. Terminalia carolinensis is a large buttressed tree found in the swamp forests of Kosrae and Pohnpei. Terminalia crassipes is a large riparian tree only known from two river systems in Palau. Terminalia rostrata, also a large tree, is only known from the tiny, 7.3 km², uninhabited Asuncion Island. Terminalia carolinensis Kaneh. E. Carolines Terminalia crassipes Kaneh. & Hatus. Palau Terminalia rostrata N. Marianas Fosberg & Falanruw V V V T(c) T(c) T(c) -R, RR R CUCURBITACEAE 2/3(1) The Cucurbitaceae family has about 845 mostly vine or liana species worldwide and can easily be recognized by the hairy palmate leaves and branched tendrils occurring at a 90º angle with the leaf petiole at the nodes. There are numerous economically important crops in this family, many of which are cultivated in Micronesia including melons, squashes, and cucumbers. There are only a few native species. Trichosanthes is one of the largest genera with about 100 species, mostly occuring in Australasia. The only record of T. hosokawae we are aware of is Fosberg’s type collection from the limestone Rock Island of Aulupse’el. It likely occurs throughout the Rock Islands, though Fosberg noted that it was rare. Trichosanthes hosokawae Fosberg Palau L WL -- ELAEOCARPACEAE 1/6(6) Elaeocarpaceae is a tropical family of trees and shrubs with a classic Gondwanan distribution of extant taxa. There are over 600 species, over half of which are within the largest genus, Elaeocarpus. They are easily recognized by the foliage. The leaves are often serrated with a swollen petiole, sometimes have domatia, and nearly always turn yellow to red before falling to the ground. The flowers are also 76 Micronesica 43(1), 2012 very distinctive, usually with fringed petals. This genus has many endemic species with narrow ranges. The center of diversity is in Southeast Asia, 60 species are endemic to Papuasia (New Guinea to Solomon Islands), and new species are still being described in Australia where the flora is well known. All Micronesian Elaeocarpus species are considered endemic. It is worth noting that although the Palau population of E. joga occurs abundantly on the volcanic island of Babeldaob, the Marianas populations are only known from limestone based soils and have been shown to be in decline (Ritter & Naugle 1999). Elaeocarpus carolinensis Koidz. Elaeocarpus joga Merr. Elaeocarpus kerstingianus Schltr. Elaeocarpus kusaiensis Kaneh. Elaeocarpus kusanoi Kaneh. Elaeocarpus rubidus Kaneh. E. Carolines Micronesia Pohnpei E. Carolines E. Carolines Palau V G V V V L T T T T T T ------- ERICACEAE 1/1(1) The following species was formerly placed in Epacridaceae and was transferred from the genus Styphelia or Cyathodes to Leptecophylla along with six other species from New Guinea and the Pacific (Weiller 1999). Epacridaceae were formerly understood as closely related to Ericaceae but as a seperate Gondwanan family. They now form the subfamily Styphelioideae within Ericaceae. Most species occur in Australia and New Zealand, but they also occur from Southeast Asia into the Pacific (Hawaii and the Marquesas) and the southern tip of South America. Ericaceae species prefer poor, acidic soils and temperate climates. Tropical members of the family rarely occur in the lowlands. Leptecophylla mariannensis is only known from Alamagan, an eleven square kilometer island located north of Saipan. The island is volcanic with a large caldera at the summit and reaches to 744 meters in elevation. Leptecophylla mariannensis occurs near the caldera up to about 700 meters (Sleumer 1963). Leptecophylla mariannensis (Kaneh.) C.M.Weiller N. Marianas V S RR EUPHORBIACEAE 12/21(8) Euphorbiaceae, the spurge family, used to include what are now Phyllanthaceae and Putranjavaceae. It is a large family of nearly 6,000 species with its center of diversity in the Indomalayan tropics. There are few universal vegetative characters for this family but the plants often have leaves of irregular size with glands near or at the base or petiole and/or with stipules present. The flowers are unisexual and the fruits are nearly always three-parted. Claoxylon has about 80 species distrib- Costion & Lorence: Endemic Plants of Micronesia Checklist 77 uted from Madagascar to the Pacific. The flowers are very small and inconspicuous born on spikes in the axils of the leaves. Croton is a large pantropical genus with about 1300 species. A number of species are used for traditional medicine, food, and even research for potential biofuels. Croton saipanensis is only known from Saipan. Euphorbia is one of the largest genera of flowering plants. Most species are succulent or xerophytic and have toxic white latex. There are a number of weedy Euphorbia species in Micronesia. The native ones, including the endemic E. gaudichaudii, tend to be small herbs or shrubby strand plants. Macaranga is a palaeotropic genus of about 240 species. They are often colonizers found in disturbed sites or primary vegetation, and many species have been documented to have symbiotic relationships with ants that live in the hollow stems. Claoxylon carolinianum Pax & Hoffm. Claoxylon longiracemosum Hosok. Claoxylon marianum Mueller-Argoviensis Cleidion sessile Kaneh. & Hatus. Croton ripensis Kaneh. & Hatus. Croton saipanensis (Hosok.) Hosok. Euphorbia gaudichaudii Boissier Macaranga thompsonii Merr. Pohnpei Palau S. Marianas V V L T T T-S -U C Palau Pohnpei S. Marianas Micronesia Marianas L V -G L T T-S -S T-S -R --C FABACEAE 27/46(12) The legume family is the third largest family of flowering plants with approximately 19,400 species worldwide. They are easy to distinguish, having alternate, usually compound leaves with stipules and fruits usually as legumes. Fabaceae is a very economically important family with many crops and nitrogen fixing plants. Although there are numerous introduced and weedy Fabaceae species present in Micronesia, there are also a number of endemics with very narrow ranges. Both species of Parkia have very small population sizes and are single island endemics. Serianthes nelsonii is endemic to the islands of Guam and Rota. There is only one known mature tree left on Guam (Stone 1970; Wiles 1998). The population on Rota is more intact with about 120 trees, though it is expected to decline from lack of regeneration (Wiles 1998). Parkia parvifoliola qualifies for Endangered status under the IUCN red listing criteria (Costion et al 2009) and Serianthes nelsonnii is listed as Critically Endangered (Wiles 1998). Mucuna pacifica and Rhynchosia calosperma are only known from Saipan, Tinian, and Rota, and Derris mariannensis is only known from the island of Rota. Tephrosia mariana is endemic to the Micronesia bioregion but only known from Guam and Chuuk. Canavalia megalantha Merr. Crudia cynometroides Hosok. Cynometra yokotai Kaneh. Marianas Palau Chuuk -V -- WL T T -U -- 78 Micronesica 43(1), 2012 Dalbergia hosokawae Costion & Lorence Dalbergia palauensis Hosok. Derris mariannensis Hosok. Mucuna pacifica Hosok. Parkia korom Kaneh. Parkia parvifoliola Hosok. Rhynchosia calosperma Warb. Serianthes nelsonii Merr. Tephrosia mariana DC. & Hosok. Palau V WL -- Palau S. Marianas S. Marianas Pohnpei Palau S. Marianas S. Marianas Micronesia V --V V ---- WL WL -T T(c) -T S ---R RR -R -- GENTIANACEAE 1/2(1) Gentianaceae is a cosmopolitan family with over 1,600 species occurring worldwide, mainly in temperate regions. Their foliage is distinctive in having opposite leaves with the two petioles joining at the base. Fagraea is a genus of about 75 species, one of which is now a popular ornamental in the Pacific, particularly in Hawaii. Fagraea berteroana is native to Australia, New Guinea, Micronesia, and east to the Marquesas. The Palau endemic F. ksid is very close to F. berteroana in its morphology and may be derived from it. It is easily distinguished from the latter by its elongated ovoid fruit and larger flowers with stamens and style that are not exserted. Fagraea berteroana in Palau also tends to occur as an epiphyte in the forest while F. ksid occurs as a tree in the savannas or savanna edges and along ridgelines. Fagraea ksid Gilg & Gilg-Ben. Palau V T C GESNERIACEAE 1/4(4) Gesneriaceae is almost entirely tropical and is close to Lamiaceae, the mint family. All species are either herbaceous or soft stemmed trees or shrubs. They have opposite serrated leaves often with soft hairs or pubescence and flowers with bilateral symmetry. The genus Cyrtandra has radiated substantially throughout the Pacific with a high percentage of single island endemics. It has nearly 600 known species and is most diverse in Southeast Asia. Recent molecular work strongly suggests that the species in the Pacific are Southeast Asian derived and have radiated from a single dispersion event followed by stepping stone migration across the Pacific (Cronk et al. 2005). Micronesia has four species, and all are endemic with limited distributions. Cyrtandra kusaimontana Hosok. Cyrtandra palawensis Schltr. Cyrtandra todaiensis Kaneh. Cyrtandra urvillei C.B. Cl. Kosrae Palau Palau E. Carolines V V L V -WL S -- U-R U-C -U Costion & Lorence: Endemic Plants of Micronesia Checklist 79 LAMIACEAE 8/16(1) The mint family was recently expanded to include many, but not all, previous members of Verbenaceae. It has worldwide distribution with many important economic plants, particularly herbs and spices. Plants in this family often have aromatic leaves, square shaped stems, bisymmetric flowers with an upper and lower lip, and branches of woody species often have distinct lenticels. Callicarpa, a genus of up to 140 recognized species, was formerly placed in Verbenaceae. It has global distribution, but most species occur in East and Southeast Asia. There is very little information available on C. lamii. It even escaped Stone’s (1970) attention in the Flora of Guam, and thus it is probably very similar to the widespread C. candicans. Fosberg & Sachet (1980) also noted that it was only weakly distinct from C. candicans, and that the varieties of the latter species they recognized and its relationships with other Indopacific species are also unclear requiring further study. Kawakubo (1986) also noted a high degree of morphological variation in endemic Callicarpa of the Bonin Islands. Molecular studies may revise species concepts in this genus. Callicarpa remains unplaced within the Lamiaceae. Callicarpa lamii Hosok. Marianas -- S -- MALVACEAE 18/23(6) The Malvaceae family now includes Tiliaceae, Sterculiaceae, and Bombacaceae as subfamilies in a larger family concept, Malvaceae sensu lato, which includes over 4,000 species. The family can often be recognized without fertile material by its alternate stipulate leaves, palmate venation or palmately compound leaflets, and stellate hairs on the leaves. The branches often have “strong” or very fibrous bark that peels down the branch instead of breaking clean, often with mucilage. Hibiscus tiliaceus, a common Pacific strand and wetland plant, is exploited for just these characters. Long strips of bark are used to extract the juice of sakau in Pohnpei, giving it the characteristic slimy texture. Other important economic plants in this family include cotton and chocolate. Micronesia’s endemics range from canopy trees to pioneer shrubs. Heritiera longipetiolata occurs rooted in crevices in dissected limestone slopes and plateaus in the Marianas. It is listed as Vulnerable on IUCN redlist and known outside the Marianas only from Pohnpei. Sterculia is a pantropical genus of 150 species. Sterculia palauensis is a large buttressed tree only found on Palau’s limestone islands, and S. ponapensis is known only from Pohnpei and Yap. Trichospermum is predominantly a Malesian genus with its diversity centered in New Guinea. Two species occur in Micronesia, and are both are endemic. They are common shrubs occurring in primary vegetation or at edges of savannas. Heritiera longipetiolata Kaneh. Melochia villosissima Merr. Micronesia Micronesia L V T S R U 80 Micronesica 43(1), 2012 Sterculia palauensis Kaneh. Sterculia ponapensis Kaneh. Trichospermum ikutai Kaneh. Trichospermum ledermannii Burret Palau Carolines Yap Palau L V -V T(c) T S S ---A MELESTOMATACEAE 3/8(6) The Melestomataceae family is a large pantropical to substropical family with over 5,000 species. The center of diversity is in the neotropics. Members of this family are easy to distinguish by their opposite leaves with three or more conspicuous veins ascending from the base with tertiary veins occurring perpendicular to the midrib. The flowers are also distinct in having porose anthers with conspicuous connectives or appendages. Astronidium has 70 species from Indomalesia to the Pacific. Three are now recognized as endemic in Micronesia with the former Astronidium kusaianum reduced to synonomy under A. carolinense. Medinilla is a palaeotropic genus of shrubs and lianas. In Micronesia the three endemics species occur as lianas or climbing shrubs. Astronidium carolinense (Kaneh.) Markgr. Astronidium palauense (Kaneh.) Markgr. Astronidium ponapense (Kaneh.) Markgr. Medinilla blumeana Mansf. Medinella diversifolia Kaneh. Medinilla medinilliana (Gaud.) Fosberg & Sachet Chuuk -- T -- Palau V T(u) C Pohnpei V T -- Palau Kosrae Marianas V V -- WL WL S-WL -RR C MELIACEAE 4/5(1) Meliaceae, the mahogany family, is a pantropical family with over 600 species. Mahogany is native to Central and South America, but it is widely cultivated in the Pacific for its esteemed timber. It grows well in the Pacific where it is free of natural pests and is considered a low risk of becoming an invasive naturalized weed. Not many native Meliaceae species occur in Micronesia, though recent molecular studies (Muellner et al. 2005) have indicated that some complex and variable species, following Pannell’s wide species concept (1992), contain more than one taxon each. Both Aglaia palauensis and A. ponapensis were reduced to synonymy under A. mariannensis in Pannell’s revision (1992). These taxa may be revived pending the results of future molecular work on the Micronesia populations. Aglaia is an Indomalayan genus of over 100 arborescent species mostly found in the moist tropics. In Micronesia they occur as small understory trees with new growth that has a conspicuous reddish brown pubescence. The Mariannas population is restricted to Costion & Lorence: Endemic Plants of Micronesia Checklist 81 limestone forest communities, while the Palau and Eastern Caroline populations are found on both volcanic and limestone forests. Aglaia mariannensis Merr. Micronesia G T(u) C MORACEAE 4/11(2) The fig family has about 1125 species mostly in the tropics and particularly abundant in the lowland rainforests of Africa and the Americas. All species have conspicuous milky white latex, and many species have alternate leaves with a prominent terminal sheathing stipule. Ficus is by far the largest genus in the family with 800 species. Micronesia has several native Ficus species but only one endemic. Ficus saffordii, known from Marianas and Palau, is a large banyan fig that starts out as an epiphyte. It was treated as a variety of F. microcarpa by Stone (1970) but is currently recognized as a distinct species (Berg & Corner 2005). Artocarpus is a Malesian and Pacific genus with 45 species. Several species are cultivated for food and timber including A. heterophyllus, commonly known as jackfruit, and several species of breadfruit including A. mariannensis, which was not recognized by Berg et al. (2006) in their Flora Malesiana treatment. They treat it as a synonym of A. altilis, which is regarded as an introduction to Micronesia. However, A. mariannensis (dugdug or chebiei) is a seeded breadfruit that grows wild in Palau and the Mariana Islands and has long been cultivated throughout Micronesia, especially on the atoll islands. It hybridizes naturally with the introduced breadfruit A. altilis, and the numerous hybrids are only found in Micronesia (Ragone 2010, www.ntbg.org/breadfruit/breadfruit/). Breadfruit is an important staple on Pohnpei particularly and to a lesser extent on other islands in Micronesia. It is also the favored timber for constructing outrigger canoes because of its durability and light weight. Artocarpus mariannensis Trecul Ficus saffordii Merr. Micronesia Micronesia L -- T E-T --- MYRTACEAE 3/12(7) Myrtaceae is a large tropical to warm-temperate family of over 4,600 species. They generally have opposite leaves with gland dots and ethereal oils that make the leaves aromatic when crushed. The bark is often flakey and the stamens are often colored and numerous. Syzygium, a palaeotropical genus of over 1,000 species, has often been confused with Eugenia. Its center of diversity is in Southeast Asia, where there are many undescribed species. Eugenia is now recognized as a neotropical-centered genus, though a few such as E. reinwardtiana, native to Australia, Southeast Asia, Micronesia, and other Pacific Islands, do occur outside this range. Fosberg et al. (1979) treated all of the Micronesia plants in this complex under Eugenia. Most of these have been transferred back to their previous 82 Micronesica 43(1), 2012 names under Syzygium while others are retained as Eugenia. For two, Syzygium thompsonii and Syzygium trukensis, new combinations were required. We follow Schmid’s (1972) treatment for distinguishing Eugenia and Syzygium in Micronesia and found the material fits this classification scheme. Micronesia’s Eugenia species were formerly treated as Jossinia and many of the Syzygium species were formerly treated as Jambosa. The two Marrianas endemics in Eugenia are very closely allied and were even suspected by Stone (1970) to be potentially different growth forms of the same species. Both names are retained here until molecular or others studies provide evidence to support their synonymy. Eugenia bryanii Kaneh. Eugenia palumbis Merr. Syzygium thompsonii (Merr.) N. Snow Syzygium trukensis (Hosok.) Costion & E. Lucas Myrtella bennigseniana (Volk.) Diels Syzygium palauensis (Kaneh.) Hosok. Syzygium stelechanthum (Diels) Glassman Guam Marianas S. Marianas Chuuk -L L -- S S T(c) -- -C --- Micronesia Palau E. Carolines V G V S T T-S ---- OLEACEAE 2/2(1) The olive family contains over 600 species worldwide, all woody. The leaves are opposite, lacking stipules, and may be simple or compound. The flowers are four to five-merous, often aromatic, and are especially distinctive by nearly always having only two stamens. Aside from olives, other economically important members this family include many ornamentals such as lilacs, jasmines, and forsythia. Micronesia’s endemic, Jasminum marianum, is common and widespread on open limestone forests in the Marianas. Jasminum marianum DC. Marianas G S C PHYLLANTHACEAE 8/25(13) Phyllanthaceae, a family of 1,745 species worldwide, was split from Euphorbiaceae as a result of molecular studies and various morphological features. Phyllanthaceae species lack latex, the leaves often have petioles with a pulvinus at the base and lack glands, and the fruits have two seeds in each carpel. Many species also have an explosively dehiscent fruit that leaves a persistent central column behind. Both Cleistanthus and Glochidion are paleaotropic genera with about 140 and 300 species respectively. Wagner & Lorence (2011) recently transferred the Pacific oceanic island Glochidion species into Phyllanthus and we cite their new names in parentheses below each basioym. This group is very speciose in the Pacific and Micronesia specifically. The expanded genus Phyllanthus comprises over Costion & Lorence: Endemic Plants of Micronesia Checklist 83 1300 species. Species in the Glochidion group can be difficult to differentiate and require further in-depth revision. The Micronesian Phyllanthus taxa are distinctive with small and numerous, two-ranked leaves making them very easy to identify in the field. They occur either in the savannas (P. palauensis and P. saffordii), or on limestone bluffs (P. marianus and P. rupiinsularis). Cleistanthus carolinianus Jabl. Palau G T Cleistanthus insularis Kaneh. Palau V T Cleistanthus morii Kaneh. Chuuk -T Glochidion kanehirae Hosok. Carolines --(=Phyllanthus kanehirae (Hosokawa) W.L. Wagner & Lorence) Glochidion macrosepalum Hosok. Palau G S (=Phyllanthus macrosepalus (Hosokawa) W.L. Wagner & Lorence) Glochidion marianum Muell.-Arg. Guam G T-S (=Phyllanthus mariannensis W.L. Wagner & Lorence) Glochidion palauense Hosok. Palau G T (=Phyllanthus otobedii W.L. Wagner & Lorence) Glochidion ponapense Hosok. Pohnpei V T-S (=Phyllanthus ponapense (Hosokawa) W.L. Wagner & Lorence) Glochidion senyavinianum Glassman Pohnpei V T-S (=Phyllanthus senyavinianus (Glassman) W. L. Wagner & Lorence) Glochidion websteri Fosberg Palau --(Phyllanthus websteri (Fosberg) W. L. Wagner & Lorence) Phyllanthus marianus Muell.-Arg Micronesia L S Phyllanthus palauensis Hosok. Palau V S Phyllanthus rupiinsularis Hosok. Palau L S Phyllanthus saffordii Merr. Marianas V S U U ---C C ---A C-A --- PUTRANJIVACEAE 1/5(5) This family was formerly included in Euphorbiaceae, but molecular work has placed it as a separate lineage in its own family. It is a small pantropical family with only three to four genera and 210 species, 200 of which are in Drypetes. They have two ranked leaves that are often asymmetrical at the base. The fruits are one-seeded and have persistent flap-like stigmas at the apex. The leaves of many species contain mustard oils and are reported to have a peppery taste. The endemics are found in the Western Carolines and Northern Marianas. Drypetes dolichocarpa is only known from Saipan, and D. rotensis is only known from Rota. Drypetes carolinensis Kaneh. Drypetes dolichocarpa Kaneh. Drypetes nitida Kaneh. Drypetes rotensis Kaneh. Drypetes yapensis Tuyama Yap Marianas Palau S. Marianas Yap --G --- T T T T T --C --- 84 Micronesica 43(1), 2012 PRIMULACEAE 5/14(13) Recent molecular studies suggest that Myrsinaceae is not a monophyletic family. Myrsinaceae was traditionally separated from Primulaceae on the basis of it members being woody verses herbaceous taxa in the latter. Molecular evidence has shown that many herbaceous taxa from Primulaceae are included within Myrsinaceae. Field characters for distinguishing the woody Primulaceae however are still good. They have characteristic “dash” or line shaped punctations visible when held to light. Some have dot and dash shaped punctations. Only one herbaceous Primulaceae species is present in Micronesia, Lysimachia mauritiana, and it has a widespread distribution across the Pacific. All woody species of Primulaceae in Micronesia are endemic. Some, such as Maesa palauensis are widespread commonly occurring species, though not locally abundant. Others such as Maesa canfieldiae are rare and poorly known. Discocalyx ladronica is so poorly known that its island locality within the Marianas is totally unknown. It is only known from the type collection and allegedly very distinct from the more common D. megacarpa. Stone (1970) suggested a potential locality mix up; however, it is also certainly feasible that it may have become rare or even possibly extinct after or during WW II. Species of Myrsine can often be distinguished by their leaves, rather densely clustered leaves near ends of branches and reddish-purple petioles. Discocalyx ladronica Mez Discocalyx megacarpa Merr. Discocalyx mezii Hosok. Discocalyx palauensis Hosok. Discocalyx ponapensis Mez Embelia palauensis Mez Maesa canfieldiae Fosberg & Sachet Maesa carolinensis Mez Maesa palauensis Mez Maesa walkeri Fosberg & Sachet Myrsine carolinensis (Mez) Fosberg & Sachet Myrsine ledermannii (Mez) Fosberg & Sachet Myrsine palauensis (Mez) Fosberg & Sachet Marianas Marianas Palau Palau Pohnpei Carolines Palau E. Carolines Palau S. Marianas Pohnpei -L G L V V L V L -V -S T(u) T T-S WL T-S T-S S T-S T-S -C U ---RR ----- Pohnpei V T-S -- Palau V T(u) C RHAMNACEAE 4/4(2) Rhamnaceae, the buckthorn family, has over 900 species worldwide, mostly trees and shrubs, or sometimes climbers. They are most easily recognized by their Costion & Lorence: Endemic Plants of Micronesia Checklist 85 flowers having stamens opposite the petals, which are often hood or cup shaped surrounding the stamens. The petals are often smaller than the sepals and can fall off, making it easy to confuse the sepals for petals. Many species are thorny and some are nitrogen fixing. Alphitonia is a small genus distributed from Southeast Asia into the Pacific. Alphitonia carolinensis is common in the Western Carolines and is most abundant in canopy gaps and edges of savannas. Ventilago is also a small genus, palaeotropic in distribution with most species occurring in Australasia. Although V. nisidai is not very well known, it has been recorded as a liana collected from the edge of swamp forest on Babeldaob. Alphitonia carolinensis Hosok. Ventilago nisidai Kaneh. W. Carolines Palau V V T WL-S C -- RUBIACEAE 22/66(45) Rubiaceae, the coffee family, is the third largest native vascular plant family in Micronesia and the second largest in terms of number of endemic species, exceeded only by the orchids. Members of this family can easily be recognized vegetatively. They have opposite leaves with an inter- or intrapetiolar scar or stipule. The stipule or stipule scar extends across the stem at the node between the two petiole bases. The flowers have an inferior ovary and there is often a scar at the fruit apex left by the calyx and fallen corolla. Micronesia has a number of narrow endemics in this family including Hedyotis kanehirae, known only from Alamagan and Timonius salsedoi, known only from the island of Malakal. Hedyotis, Psychotria, and Timonius are by far the most speciose genera in Micronesia. Hedyotis is a paleotropical genus most diverse in SE Asia. Many species in this genus have been transferred back and forth from Oldenlandia, which is represented in Micronesia by one native and several weedy species. In Micronesia, Hedyotis species range from very small herbs to large shrubs and occur in open savannas, clearings, and under the forest canopy. Psychotria is one of the largest of Angiosperm genera with perhaps 1,650 species (Nepokreoff et al. 1999). Most of the Micronesian endemics are shrubs or small understory trees. One of particular interest, P. diospyrifolia, occurs as a climber or scandent shrub which is rare for the genus. Timonius is a palaeotropic genus of 150-180 species. These plants are dioecious trees or shrubs with axillary inflorescences. All of Micronesia’s endemics in Timonius are restricted to the Western Carolines with the exception of T. ledermannii which is endemic to Chuuk and Pohnpei. Atractocarpus carolinensis (Valeton) Puttock Badusa palauensis Valeton Bikkia palauensis Valeton Hedyotis aimiriikensis Kaneh. Hedyotis cornifolia Kaneh. Carolines -- T -- Palau Palau Palau Palau G L V V T S S H C C --- 86 Micronesica 43(1), 2012 Hedyotis cushingiae Fosberg Hedyotis divaricata (Valeton) Hosok Hedyotis fruticulosa (Volk.) Merr. Hedyotis kanehirae (Hatusima) Fosberg Hedyotis korrorensis (Valeton) Hosok Hedyotis laciniata Kanehira Hedyotis megalantha Merr. Hedyotis ponapensis (Valeton) Kaneh. Hedyotis sachetiana Fosberg Hedyotis scabridifolia Kaneh. Hedyotis suborthogona Hosok. Hedyotis tomentosa (Valeton) Hosok. Hedyotis tuyamae Hosok. Hedyotis uncinelloides (Valeton) Hosok. Ixora casei Hance Ixora triantha Volk. Morinda latibractea Valeton Morinda pedunculata Valeton Ophiorrhiza palauensis Valeton Psychotria andersonii Fosberg Psychotria arbuscula Volk. Psychotria cheathamiana Kaneh. Psychotria diospyrifolia Kaneh. Psychotria hombroniana (Baill.) Fosberg Psychotria hosokawae Fosberg Psychotria lasianthoides Valeton Psychotria malaspinae Merr. Psychotria mariana Bartl. ex DC. Psychotria merrillii Kaneh. Psychotria mycetoides Valeton Psychotria rhombocarpa Kanehira Psychotria rhombocarpoides Hosok. Psychotria rotensis Kaneh. Timonius albus Volk. Timonius corymbosus Valeton Timonius ledermannii Valeton Timonius korrensis Kaneh. Timonius mollis Valeton Timonius subauritus Valeton Timonius salsedoi Fosberg & Sachet Yap W. Carolines Micronesia N. Marianas V V V V D S S S ---RR Palau Marianas Guam E. Carolines Palau Marianas Palau Palau Palau Pohnpei V V V V V V V G V V S H H H S H-S H H S H C-A ------C --- Micronesia Micronesia Palau Palau Palau Guam Yap Palau Palau Micronesia G -L V G --L V G S S T(u) S-T H -S T(u) WL-S S C C U C U ---U -- Kosrae Pohnpei Guam Micronesia Pohnpei Palau Kosrae Pohnpei Micronesia Yap Palau E. Carolines Palau Palau Palau Palau V V -L V V V V G -G V L V V V T-S S S-T T T-S S T-S S T-S T-S T-S T T T(u) S T(u) ---C --C -------C RR Costion & Lorence: Endemic Plants of Micronesia Checklist 87 RUTACEAE 2/5(3) Rutaceae is the citrus family with over 1800 species worldwide. The leaves are usually opposite and often compound with distinct gland dots. The foliage of species with simple leaves could potentially be confused with Myrtaceae, which also have opposite leaves with gland dots. The aroma of the oils present in the citrus family however, is noticeably different from Myrtaceae when the leaves are crushed. Melicope has 150-233 species distributed from Madagascar and the Indo-Himalaya region east to Hawaii and the Marquesas. There are different viewpoints on the generic limits of this genus, though these do not affect the status of the Micronesian taxa. In Micronesia Melicope occurs as a shrub or small understory tree and is more or less inconspicuous. Melicope ponapensis has unifoliate leaves that are opposite or in whorls. Both Palau species have trifoliate leaves and are very similar. Melicope trichantha occurs on volcanic islands, while M. palawensis occurs on limestone islands. Melicope trichantha also has stouter branchlets and petioles, and the petals and sepals are larger with a velvety pubescence (Hartley 2001). Melicope palawensis (Lauterb.) T.G.Hartley Melicope ponapensis Lauterb. Melicope trichantha (Lauterb.) T.G.Hartley Palau L S C Pohnpei Palau V V T-S S-T --- SAPINDACEAE 7/9(3) Sapindaceae is a large family distributed worldwide. It was recently expanded to include Aceraceae, the maples, and other small groups. They are an important family in tropical Australia and Southeast Asia. Tropical members can usually be distinguished by their pinnately compound leaves with a small terminal rachis tip protruding at the leaf apex, ridged rachis, and swollen petioles. Most Sapindaceae flowers have an extrastaminal disc, a nectary disc that occurs outside the whorl of stamens, or the whorl of stamens sits on top of the disc. This a unique character among the flowering plants, most nectary discs being intrastaminal, occurring inside the whorl of stamens. Allophylus holophyllus was noted by Stone (1970) to be rare on Guam and potentially synonymous with A. timorensis, though he did distinguish it from the latter by having an entire leave margin and densely pubescent inflorescence axis. We retain the name until molecular data or other studies prove otherwise. Cupaniopsis guillauminii has been placed under several different names spanning three genera over the years. Van der Ham (1977) made the correct combination under Cupaniopsis but incorrectly included the Fijian endemic C. concolor. This species concept was subsequently rejected by both Smith (1985) and Adema (1991), thus both the Chuuk and Fiji endemics are retained. Elattostachys palauensis is only known to us from the type specimen which was collected from the limestone Rock Islands in Koror State. 88 Micronesica 43(1), 2012 Allophylus holophyllus Radlk. Cupaniopsis guillauminii (Kaneh.) Adema Elattostachys palauensis Hosok. S. Marianas Chuuk L -- S T R -- Palau L T -- SAPOTACEAE 3/5(3) Sapotaceae is a tropical family with roughly 1,100 known species. They have alternate leaves often clustered toward branch tips with white latex. The terminal buds are often covered with brownish appressed hairs and the petioles are often described as bottle shaped. The genus Manilkara is currently under revision. Preliminary molecular results suggest that the genus is not monophyletic and the Palau species along with others may be transferred to a different genus. Manilkara udoido is a distinctive tree with a curious distribution, only occurring in southern Babeldaob, where it can form dominant stands. The two Micronesian species of Planchonella, P. obovata and P. calcarea, were placed in Pouteria by Fosberg et al. (1979), but they have both been transferred back to Planchonella. Planchonella calcarea is poorly known. It probably occurs throughout the limestone islands of Palau but has only been recorded from one locality aside from the type and was noted to be rare (Fosberg and Sachet 1980). Palaquium is a genus of about 120 species from Southeast Asia to Australia and the Pacific. The latex of some species has been intensively studied and exploited for its excellent electrical insulating properties. Palaquium karrak is a tall canopy tree occurring in the lowland forests of Pohnpei. Manilkara udoido Kaneh. Palaquium karrak Kaneh. Planchonella calcarea (Hosok.) P. Royen Planchonella micronesica (Kaneh.) Kaneh. ex H.J. Lam Palau Pohnpei Palau V V L T T T A,RR --- Kosrae V -- -- SALICACEAE 4/6(3) Many of the tropical members of this family were traditionally placed in a separate family, Flacourtiaceae. This family was never regarded as a solid natural group but has only recently been dissolved and divided into several separate, unrelated families. All of the Micronesian taxa were transferred to Salicaceae except for Pangium edule, the football fruit, which was transferred to Achariaceae. Salicaceae have distinct “salicoid” teeth or serrations on the leaf blade which are unique by having a vein extending to the apex of the tooth which is tipped by a circular gland or hair. Casearia is a tropical genus of roughly 180 species. They are notoriously difficult to distinguish, and a good hand lens or a dissecting microscope is required for the Micronesian taxa. Xylosma is a pantropical genus containing Costion & Lorence: Endemic Plants of Micronesia Checklist 89 about 85 species. They are often small shrubby plants with thorns and many are used for ornamental hedges. The Micronesian endemic, X. nelsonii, is an unarmed shrub occurring in open areas along the coast or in savannas. It is only known from the Marianas and Chuuk. Casearia cauliflora Volk. Casearia hirtella Hosok. Xylosma nelsonii Merr. Yap Palau Micronesia -G V T T S -C -- SOLANACEAE 2/4(2) Solanaceae is the nightshade family, which is famous for both its many poisonous and nutritious plants. There are some 2,460 species found worldwide. A great number have been exploited by humans, some for the sustenance they provide such as tomato, potato, chili, eggplant, and goji berries, and others for their alkaloids such as tobacco, Datura, and Brugmansia. Solanum is the largest genus with 1,2001,700 species. The genus occurs worldwide but is most diverse in South America. Solanum guamense is endemic to the Marianas and only occurs on limestone cliffs along the coast. Solanum mariannense is very poorly known and has only been recorded from the island of Rota (Fosberg et al 1979). Solanum guamense Merr. Solanum mariannense Hosok. Marianas S. Marianas L -- S S --- URTICACEAE 11/24(7) The Urticaceae is the stinging nettle family. To “urticate” means to produce a stinging or itching sensation. Many members of this family have glandular hairs that contain mild to severe neurotoxins in them. The sting can vary from a mild itch, as in many temperate herbaceous Urtica species, to severe pain requiring medical attention as in some arborous Dendrocnide species. Dendrocnide latifolia, native to Micronesia can produce a mild but harmless sting. The flowers of this family are small and mostly wind pollinated and thus distinctively non-showy. Elatostema is a large genus of some 300 palaeotropic species. The species generally occur as herbs to small shrubs without stinging hairs. Many of the Micronesia endemics occur as herbs along river banks where it is moist year round. Pipturus is an Australasian genus of approximately 50 species stretching from Madagascar to the Pacific. It has radiated substantially in the Pacific, especially Hawaii. The Palau endemic Pipturus micronesicus may be derived either from the widespread strand plant P. argenteus, or from P. subinteger, both native to Palau. It is very poorly known. Elatostema calcareum Merr. Elatostema fenkolense Hosok. Elatostema flumineorupestre Hosok. Micronesia Kosrae Pohnpei L V V H H H ---- 90 Micronesica 43(1), 2012 Elatostema kusaiense Kaneh. Elatostema stenophyllum Merr. Elatostema stoloniforme Kaneh. Pipturus micronesicus Kaneh. E. Carolines Guam Palau Palau V V V L H H H S ----- VITACEAE 2/5(1) The grape family contains about 850 species and is found worldwide, though it is more abundant in the tropics. The leaves are palmately compound, veined, or lobed. Vitaceae vines and lianas can be distinguished from other vines by the tendrils that occur directly opposite the leaves at a 180º angle. The family is represented by two native genera in Micronesia. Leea was formerly placed in its own family, Leeaceae. It is now placed as subfamily Leeoidea within the Vitaceae. Leea guineensis and L. indica are both widespread species that occur as understory trees or shrubs in the Indomalesian region. Cayratia is represented by over 60 species in the palaeotropics and Pacific. Preliminary molecular work indicates it is a paraphyletic genus (Soejima 2006). Of the three native Cayratia species in Micronesia, one is allegedly endemic to Palau. It is so poorly known that the only information about the species is from the protologue and type specimen. Cayratia palauana (Hosok.) Suesseng. Palau L WL -- NEW COMBINATIONS AND NAMES THELYPTERIDACEAE We follow Smith et al. (2006) in their circumscription of Thelypteridaceae genera. The five species listed below are now referable to Cyclosorus Link, and therefore require the following new combinations in that genus. Cyclosorus carolinensis (Hosokawa) Lorence, comb. nov. Basionym: Dryopteris carolinensis Hosokawa, Trans. Nat. Hist. Formosa 26: 74. 1936. Type: Palau Is. Todai-san, 15 Oct. 1933, Hosokawa 7518 (Holotype TAI; Isotype BISH 498211!). Christella carolinensis (Hosokawa) Holttum, Kew Bull. 31: 307. Thelypteris carolinensis (Hosok.) Fosberg, Smithsonian Contr. Bot. 45: 4. 1980. Note: The club-shaped yellow-orange glands on lower surface of the pinnae are distinctive. Cyclosorus gretheri (W. H. Wagner) Lorence, comb. nov. Basionym: Lastrea gretheri W. H. Wagner, Pacific Sci. 2: 214, fig. 1. 1948. Type: Mariana Islands. Rota, growing on bare coral-limestone rock in crevice in rather exposed situation on a bank along road at 800 ft. altitude on the north slope of the plateau of Rota, 27 July 1947, D. F. Grether 4468 (Holotype UC; Isotype BISH Costion & Lorence: Endemic Plants of Micronesia Checklist 91 498913!). Thelypteris gretheri (W. H. Wagner) B. C. Stone, Micronesica 2: 135. 1967. N. Marianas Cyclosorus guamensis (Holttum) Lorence, comb. nov. Basionym: Christella guamensis Holttum, Allertonia 1: 222. 1977. Type: Mariana Islands. Guam, by small stream, Grether 4384 (Holotype: BISH! Isotype UC). Thelypteris guamensis (Holttum) Fosberg & Sachet, Amer. Fern J. 71(3): 82 (1981). 1981. Cyclosorus palauensis (Hosokawa) Lorence, comb. nov. Basionym: Meniscium palauense Hosokawa, Trans. Nat. Hist. Soc. Formosa 28: 148. 1938. Type: Palau, Babeldaob, in a primary forest on Mt. Grittel near Ngakurao, Hosokawa 9265. (Holotype: TAI, digital image seen!). Thelypteris palauensis (Hosok.) C. F. Reed, Phytologia 17: 300. 1968. Cyclosorus rupiinsularis (Fosberg) Lorence, comb. nov. Basionym: Dryopteris rupicola Hosokawa, Trans Nat. Hist. Soc. Formosa 26: 73. 1936, non C. Chr. 1917. Type: Caroline Islands. Palau, on elevated coral rock, Hosokawa 7440 (Holotype TAI; digital image seen!; Isotype BISH). Glaphyropteris rupicola (Hosokawa) Hosokawa, Trans. Nat. Hist. Soc. Formosa 32: 285. 1942. Christella rupicola (Hosokawa) Holttum, Allertonia 1: 217. 1977. Thelypteris rupi-insularis Fosberg, Smithsonian Contr. Bot. 45: 5 (1980). Note: There is already a Cyclosorus rupicola Ching & K.H. Shing, Fl. Fugianica 1: 598. 1982, based on a different type, thus precluding the use of this epithet. This necessitates using the next available epithet, namely that of Thelypteris rupiinsularis Fosberg. FABACEAE The basionym Dalbergia oligophylla Hosokawa is invalid. It was described by Hosokawa (1934) after Dalbergia oligophylla Baker ex. Hutch & Dalziel was validly published in the Flora of West Tropical Africa (Hutchinson & Dalziel 1928). Dalbergia oligophylla is endemic to Cameroon and classified as Endangered (Cheek 2004). We therefore propose the following new name for this species. Dalbergia hosokawae Costion nom. nov. Basionym: Dalbergia oligophylla Hosokawa, Trans. Nat. Hist. Soc. Formosa 24: 415. 1934. Type: Palau, Ailai & Aimiliiki-son Islands Hosokawa 7298 (Holotype TAI; Isotype MICH, digital image seen!). MYRTACEAE Two species formerly treated under Eugenia by Fosberg et al. (1979) are transferred to Syzygium.Type material was studied in collaboration with Myrtaceae expert Eve Lucas and the morphology was found to be consistent with Schmid’s (1972) clas- 92 Micronesica 43(1), 2012 sification of Eugenia and Syzygium. Eugenia is mostly restricted to the New World with a few species extending into the Old World and Pacific while Syzygium is restricted to the Old World and Pacific. We reject the recent account of Snow and Veldkamp (2010) that merges Eugenia thompsonii and Eugenia trukensis under one name, Syzygium thompsonii (Merr.) N. Snow. The authors did not manually inspect type material of either species and based the merging of the two endemics on digital photos. Further more, the authors ignored obvious discrepencies in substrate types between the two populations. The Marianas population is well known to be restricted to limestone forests. These habitats occur on raised limestone in the Southern Marianas while the type collections of S. trukensis are clearly from volcanic soils on Mt. Witipon, Weno (Moen) Island, Chuuk. If the two populations were synonymous then an explanation for its absence on the volcanic soils of Guam is necessary. In addition the authors do not discuss the unlikely probability of such a strange disjunction in Micronesia; restricted to the Southern Marianas and Chuuk. We thoroughly reviewed the literature for the Micronesian flora and are unaware of any plants with such a disjunction. Until sufficient evidence for Snow and Veldkamp’s concept of S. thompsonii (2010) is provided, we retain the original species concepts of both taxa. Syzygium thompsonii (Merrill) N. Snow, Austrobaileya 8(2): 182. 2010. Basionym: Eugenia thompsonii Merrill, Phillipp. J. Sci., C 9: 121. 1914, Type: Mariana Islands, Guam. Jambosa thompsonii (Merr.) Diels, Engl. Bot. Jahrb. 56: 533. 1921. Type: Mariana Islands, Guam, Guam Experiment Station/Thompson 469 (Holotype K!). Syzygium trukensis (Hosokawa) Costion & E. Lucas comb. nov. Basionym: Eugenia trukensis Hosokawa, J. Jap. Bot. xiii. 281. 1937. Type: Chuuk islet Wara, Hosokawa 8434 (Holotype TAI, digital image seen!; Isotype MICH, digital image seen!) Jambosa trukensis (Hosok.) Hosok. J. Jap. Bot. 1940, xvi. 545. UNVERIFIED NAMES MENISPERMACEAE Pachygone ledermannii Diels Allegedly Endemic to: Carolines The author of this species maintained four distinct species for Malesia which were all lumped into one by Forman (1957). Pachygone ledermannii is allegedly closely allied with P. vieillardii Diels, which itself was found by Forman (1997) to be complicated by having its type specimen comprised of two separate species from different genera. For these reasons and since the Micronesian material has been excluded in the more recent revisions by Forman, we refrain from assigning endemic status to this species until further studies can be done. Tinospora homosepala Diels Allegedly Endemic to: Marianas Potentially the same as or a variety of Tinospora glabra (Burm. f.) Merrill, which Costion & Lorence: Endemic Plants of Micronesia Checklist 93 is widespread from Malaysia to Philippines, New Guinea, and New Brittain (Forman 1981). The Micronesian plants differ from latter only in having equal sepals, and Forman (1981) notes a variation in sepal length for a specimen Tinospora glabra from the Philippines. Fruits of T. homosepala are unknown and are required to resolve its taxonomic placement. Discussion Table 3 summarizes the results of this paper with the number of endemic plants per island group. The total land area per island group is provided to give additional perspective on the importance of Micronesia’s biodiversity. The Caroline Islands comprise less than half the total land area of the region yet contain 77% of all endemic plants found there. Palau alone makes up only 17% of Micronesia’s total land area but contains 37% of all endemic plants in Micronesia. The Caroline Islands and Palau in particular, clearly stand out with an exceptionally high endemism and diversity of plant species. Determining the causes and explanations for the unevenness of biodiversity on oceanic islands has generated much interest since MacArthur and Wilson’s (1967) theory of island biogeography, but until now addressing the flora of Micronesia as a whole was problematic. It is hoped that in addition to the practical and local benefits for local knowledge and conservation, Table 3: Number of endemic vascular plant species and total land area per island group Island Group Palau Yap W. Carolines Subtotal Chuuk Pohnpei Kosrae E. Carolines Subtotal Carolines Subtotal Guam S. Marianas N. Marianas Marianas Subtotal Gilbert Islands Marshall Islands Micronesia Total Land Area (km²) Endemic Species % Endemism (Spp./km²) 459 118 577 577 127 345 110 582 582 1159 1159 541 843 164 1007 1007 281 181 2628 2628 135 9 16 160 16 47 18 20 101 19 280 11 16 5 22 54 1 0 29 364 29% 8% --28% 13% 14% 16% --17% --24% 2% 3% 3% --5% 0.4% 0% --14% Sub-Region Western Carolines Eastern Carolines All Caroline Islands Marianas Far Eastern Micronesia All Micronesian Islands 94 Micronesica 43(1), 2012 this checklist will be utilized as a baseline resource for tackling larger questions on island biogeography in the Pacifc region and beyond. Addressing such questions exceedes the aims of the present study however to emphasize the biodiversity value of Micronesia on a global scale we compare our diversity results from Micronesia to that of other insular floras and recognized global biodiversity hotspots. In Table 4 we compare the endemism and diversity of plants found within the major archipelagos of the Micronesia-Polynesia biodiversity hotspot (Conservation International 2007). Up to date and reliable information on the number of indigenous and endemic vascular plants was compiled for the Marquesas (Wagner and Lorence 2002), Fiji (Watling 2005), Samoa (Whistler 1992; Whistler 2011a), the Societies (Florence 1987), Tonga (Whistler 2011b) and Hawaii (Wagner et al. 1990; Palmer 2003). The most commonly utilized approach in botanical and conservation literature to calculate plant endemism is to divide the total number of endemic species by the total number of native or indigenous species. This however only gives a measure of the relative speciation rates of lineages once established and the relative isolation of the respective islands. Species richness or richness of endemic species is more accurately calibrated to space; thus in this case the richness of native and endemic plant species per archipelago is also calculated by dividing the total number of species by the total land area (km²). When this approach is utilized the Micronesia bioregion clearly has the highest richness of Table 4: Comparison of plant diversity and endemism within and across island biodiversity hotspots. Archipelago Size Native Richness Endemic Endemism (E) Richness (km²) species (N) (N/km²) species (E) (E/N) (E ssp./km²) Micronesia-Polynesia Biodiversity Hotspot Micronesia 2,628 1,227 47% 364 Marquesas 1,050 362 34% 162 Society Islands 1,598 896 56% 273 Fiji 18,274 1,594 9% 861 Samoa 3,030 550 18% 165 Hawaii 28,311 1,255 4% 1109 Tonga 748 340 45% 15 Island Biodiversity Hotspots of the World Micronesia 2,628 ----363 New Caledonia 18,972 ----2,478 Polynesia-Micronesia 47,239 ----3,074 East Melanesia 99,384 ----3,000 Caribbean Is. 230,000 ----6,550 Philippines 297,179 ----6,091 Madagascar 600,461 ----11,600 New Zealand 270,197 ----1,865 Japan 373,490 ----1,950 Wallacea 338,494 ----1,500 30% 46% 43% 54% 30% 88% 4% 14% 6% 6% 5% 5% 4% 2% --------------------- 14% 13% 7% 3% 3% 2% 2% 0.7% 0.5% 0.4% Costion & Lorence: Endemic Plants of Micronesia Checklist 95 both native and endemic plants in the entire Micronesia-Polynesia biodiversity hotspot. Although biodiversity data for island groups such as the Cook Islands and the Phoenix Islands were not available for comparison, their floras, mostly comprised of atoll vegetation (Mueller-Dombois and Fosberg 1998) except for the high islands of the Cook archipelago, are unlikely to surpass those listed in Table 4. Hawaii is often touted as having one of the highest rates of endemism in the world, but clearly Micronesia has a richness of plant endemism per square kilometer ten times higher than Hawaii. Micronesia’s exceptionally high richness of endemic plant species is not only a regional pattern. When it is compared to the recognized island biodiversity hotspots of the world (Conservation International 2007) it surpases them all per unit area (Table 4). Only New Caledonia comes close at 13%. New Caledonia is a continental island with ancient Gondwanan links and is thus expected to have an exceptionally unique biota in comparison to oceanic islands. These data suggest that Micronesia is worthy of being recognized as a distinct biodiversity hotspot. Its richness of plant endemism is distinguishable at both the regional and global scales. The consequence of this fact means that establishment of reserve lands in Micronesia has a substantially high efficiency of maximizing species conserved per square kilometer. It also means that here, possibly more than anywhere else, the vulnerability of extinction is extremely high. The tiny islands of Micronesia may be small geographically; however, their importance to the world in maintaing reserves of unique biodiversity is not small by any means. Efforts to increase funding for collaborative projects and oppurtunities with developed countries to aid in the establishment of protected areas in Micronesia should be given high priority. The importance of funding alpha taxonomy in the Pacific and other poorly known tropical regions cannot be emphasized enough. While it is common knowledge that we cannot conserve that which we don’t know or understand, taxonomy remains a discipline in decline. Many archipelagos in other parts of the Pacific are in need of revised checklists and biodiversity inventories. A potential solution to the decline in taxonomic expertise and funding is to link up with other large funding schemes which are now available for projects relvant to issues such as climate change, the carbon credit scheme, DNA barcoding, and the Tree of Life project. Opportunities such as these can be seized to simultaneously advance alpha taxonomy where it is needed. As the world continues to specialize, taxonomic specialists must broaden their collaborative capacities to achieve outcomes for multiple concurrent platforms. Lastly, we would like to reiterate Stone’s wish that publishing this list will stimulate further floristic studies of all kinds in Micronesia. We have alluded throughout the text to ideas of potential ancestors of some of Micronesia’s endemic plants well aware of the fact that focused studies must be done for each taxa and respective lineage to reconstruct their evolutionary history. The era of bioinformatics and DNA research is well underway, which has made the tools for answering questions such as these widely available even for small undergraduate student projects. We hope this list may inspire more small projects such as these in Micronesia. Though the islands may be small, the biota they contain is diverse and complex. 96 Micronesica 43(1), 2012 Recent molecular work has already demonstrated that several genera represented in Micronesia are polyphyletic or paraphyeltic, and that some genera dispersed to islands once and speciated while other genera may have dispersed more than once. We expect that the dispersal patterns and historical biogeography here will be complex, and that the process of unraveling these evolutionary stories will provide much pleasure and interest to both the professional and casual naturalists interested in the tropical Pacific flora. Acknowledgements This work was supported by an Australian Postgraduate Fees Scholarship from the University of Adelaide and the Australian Tropical Herbarium. We would like to thank the following people for supporting the project and or providing helpful information on taxonomy of particular species or help with determining specimens: Darren Crayn, Andrew Lowe, Ed Biffin, Eve Lucas, and Allen R. Smith. We would also like to acknowledge all the people that contributed to progress of this work by collaborating on checklists for subregions within Micronesia: Ann Kitalong, Mike Balick, Tarita Holm, Robin DeMeo, Tim Flynn, and Art Whistler. We also thank the curators of the Bernice P. 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