Euphorbia virosa aka Poison Euphorbia

Euphorbia virosa is a succulent shrub or small tree. It is a spurge, in the family Euphorbiaceae. People call it poison tree, gifboom, and poisonous spurge. It grows wild from southwestern Angola through Namibia into northwestern South Africa. It lives in desert and dry shrubland. Plants grow on rocky slopes and steep cliffs in hot, dry places. They grow with other succulents and can form most of the local growth.

This plant grows slowly and forms dense clumps shaped like a candelabra. Most reach about 3.3–4.9 feet [1–1.5 metres] tall and wide. Some reach 9.8 feet [3 metres] in both height and width. Many branches grow in rings, or whorls, near the base. They spread out, then curve up, with few more branches. The main trunk stays short. It can reach one foot [0.3 metres] thick. This spurge looks like a cactus but is not one.

The grey-green stems have a blue tint and store water. A thick outer coat helps curb water loss. Narrow points split the branches into joints of uneven size. Their ridges run straight or have a slight twist. Deep grooves lie between them. Lower stems have three angles; upper stems have five to eight. Pairs of sharp spines line the ridges. New spines shine dark red, then turn grey or brown-grey. Their tips stay darker. Tiny leaves soon fall and leave the stems bare. In the wild, these short-lived leaves appear during January.

The small flower parts are called cyathia. They grow in single groups called cymes above the spine pairs. Each cyathium can reach about a third of an inch across. Its yellow glands make nectar and touch each other. In South Africa, bloom peaks from late September into early October. Small, fleshy fruits turn rusty brown and harden as they ripen. The round seeds have fine wrinkles on their surface. These traits help tell the species apart, beyond its bold branch shape.

Its dense form and spiny stems give it a strong outline. Yet its milky latex sap holds a strong poison. This sap helps guard it from most animals that browse plants. The source names black rhinoceros as an exception. Its common names point to this risk, not a food use. The supplied facts for this species give no schedule for its care. They give no frost limit or specific pest or disease advice.