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Plant Highlight: Euphorbia susannae

A strange cactus with round dark brown flower bulbs emerging from it

November 2015

South Africa’s Little Karoo region is famed for its great variety of succulent plants, and among these is Euphorbia susannae, a small clustering species which makes dome-like clumps to 4 inches tall (10 cm) and a foot across (30 cm). The chubby stems have rows of tubercles running up their sides, with each tubercle tapering to a thread-like point. On older stems the points are often worn off so that the tubercles are rounded at the tip. The stem color is green, becoming brown-tinged in strong light.

The flowering structures of Euphorbia susannae, called cyathia (the singular is “cyathium”), are held atop short stalks which emerge from brown bulbs emerge from a cactusbetween the tubercles. Each cyathium consists of a cup with 5 lobes around the outside and the tiny flowers in the middle. The small round seed capsules which follow are purplish-red.

Euphorbia susannae is cold-hardy to about 25° F (-4° C), or even lower if the soil is kept dry. Plants like plenty of sun and sharp drainage. As with many other species of Euphorbia, the plant’s white latex is poisonous and highly irritating to the eyes, so if a plant is handled, care should be taken to wash your hands.