Euphorbias of Madagascar (2019)

By Bob Williams (May 2019)

The HSCSS plant sale on April 14 was a huge success. It looked like everyone who attended walked away with a smile on their face. When looking at the quality of the plants for sale – combined with the price – this was a once-in-a-lifetime event. You could tell that Tom Degnan, who supplied most of the plants, takes a great deal of pride in his collection, and his plants reflected it.

Before the sale, my wife, Marge, Pam Schnebelen and I were looking at the Euphorbia hedyotoides on the front table. It was a good-looking plant. As we were commenting on it, Marge said, “This plant is in bloom.” We took a closer look, and the plant was in full bloom with some of the smallest yellow flowers you ever saw. I thought an article would be a good idea, and Pam suggested talking about the euphorbias of Madagascar. This article ties in with last month’s article on the spiny forest of southern Madagascar and our upcoming show, where there are categories for euphorbias of Madagascar.

As part of the documentation for the show, Pam created a list of 170-plus species of Euphorbia that are endemic to Madagascar. It took a considerable amount of time and true dedication to assemble this list, because in my research, I could not find an article that had a listing of this type.

The International Euphorbia Society (http://www.euphorbia-international.org) referenced a project being undertaken to document the 5,000 species of Euphorbia. That project is the Euphorbia Planetary Biodiversity Inventory Project at http://www.euphorbiaceae.org. For Madagascar plants, its website directed me to the Tree of Life Knowledge Information Network or TOLKIN, where a “distribution” search for euphorbias found in Madagascar (ttps://app.tolkin.org/projects/72/taxa) returned 226 pages. Most of the species names were first given in the 1800s and are no longer used.

The TOLKIN website is very interesting. It tells you who gave a species its name and the date. It may have some pictures of the species in habitat and points you to articles written about that particular species.

Looking at the list, Euphorbia milli – one of the most common of all euphorbias found in garden centers – is endemic to Madagascar. Most know this plant by its common name, crown of thorns. In looking around my house, I was surprised to find quite a few euphorbias from Madagascar, including E. guillauminiana, E. cylindrifolia, E. decaryi, E. tirucalli, E. leucodendron, E. viguieri and E. iharanae. Some additional species are E. ambovombensis, E. capsaintemariensis, E. fiherenensis, E. francoisii, E. hedyotoides and E. pachypodioides. The physical characteristics of these euphorbias are as diverse as you can get.

The plants are not confined to the “Thorn Forest” of southern Madagascar. E. iharanae is found growing in rocky coastal regions of northeast Madagascar near the town of Iharanae and a river of the same name. The small, shrublike species, like E. ambovombensis, E. capsaintemariensis, E. cylindrifolia, E. decaryi, E. fiherenensis and E. francoisii, are found in the Thorn Forest. E. pachypodioides is only found in an 8-square-kilometer area of northern Madagascar. Euphorbia viguieri is also found in the northern half of the country. The environmental diversity described in my March article on Didiereaceae has created a diverse population of Euphorbia species that grow in the desert areas in the south to semitropical regions in the north.

The plant on which I want to focus is Euphorbia hedyotoides. This plant is found in southwestern Madagascar in the Thorn Forest. It grows in subtropical and tropical dry forest regions. This plant was first described by N. E. Brown in 1911. In habitat, it grows in a shrublike form and can grow up to 8 feet tall with a canopy up to 6 feet in diameter.

Research on E. hedyotoides indicated neither the trunk nor the branches get very thick. Over time, the caudex can reach up to a foot in diameter. The caudex itself is not so much like a bulb, but more a grouping of larger, twisted, intertwined roots. This makes the plant a favorite among succulent bonsai enthusiasts.

In habitat, this is an evergreen plant that keeps its leaves all year long. The leaves are long and on the thin side. The small flowers can be either yellow or red. As with any euphorbia, beware of the sap. Take precautions when pruning. Wear gloves and glasses.

E. hedyotoides should be grown in well-draining soil. It can tolerate full sun, but can be grown in bright shade. The information I found says to moderately water the plant during the summer. Let the soil dry some before each watering. During the winter, it should be kept in a warmer area and lightly watered. This plant is not winter-hardy, but it is deer-resistant. This is a real plus in my neighborhood.

E. hedyotoides can be propagated by seed, stem cuttings or root cuttings. With some searching on the Web, it can be found for sale at a reasonable price for a small plant. In the wild, this plant is endangered due to habitat loss.