The Medusoid Euphorbias are easily identified. A (usually) large body is covered with arms. The arms may be stubby and widely spaced (euphorbia decepta), or they may be long, snake-like and closely spaced (euphorbia caput-medusae). For all of the Medusoid Euphorbias, the central thickened stem is equivalent to a caudex. It is the central storage region, and can act as a reservoir for nutrients and moisture in times of stress. Many of the Medusoids will shed their arms (branches) during extended droughts, regrowing new ones when the rains return.
Medusoid Euphorbias come from a wide range of habitats, with Cape Province, South Africa being Medusoid central; but all go through extended periods of low moisture. Cultivation for many is relatively easy; as long as attention is paid to not watering during periods of dormancy. There are generally two periods of dormancy, a long one during the late fall and winter (mid November through the end of February) and a shorter one during the peak of the summer heat (a few weeks in August and September). The arrival of the summer one is harder to predict, and over-watering in late summer can result in root rot. In spit of the sensitivity, most of the Medusoid Euphorbias do well as unprotected pot plants outdoors in Southern California during the winter.
It’s nearly impossible to find seed for most of the Medusoid euphorbias; in general, the seed is short lived (months). Vegetative propagation is easier. Most Medusoid euphorbias can be propagated from arm cuttings, although an extended period will be required before the plant is worth showing.
Species of note:
Euphorbia caput-medusae is the classic species. It is from Cape Province, with a caudex of up to 8 inches in diameter. The branches are long and serpentine. It’s the most snake-like of all the species.
Euphorbia decepta is from Cape Province South Africa. The caudex is 2 to 4 inches thick, and the branches generally less than an inch long. In habitat, the branches are deciduous, but in cultivation they stay on the plant all year. Seedlings of this plant look like World War ll floating mines.
Euphorbia flanaganii is one of the most common and easily grown of the medusoids. The central caudex is generally two or three inches across. It grows quickly, offsets readily, and can rapidly fill a large bowl with medusoid plants.
Euphorbia fortuita comes from Ladismith in Cape Province. It has a tuberous main root that merges into the main caudex, and stiff cylindrical branches usually about 4 inches long, but occasionally one will be twice as long.
Euphorbia fusca, will produce secondary heads quickly. These can be removed to start new plants.
Euphorbia gorgonis is another species from Cape Province near Grahamstown. The caudex is mostly subterranean. It has short tuberculate branches that turn red in strong light.
Euphorbia woodii is from Natal, but similar to Euphorbia flanaganii in appearance. Most of the caudex and a large turnip like root are subterranean.
Used with permission from Tom Glavich.