Euphorbia obesa

The illustrated species is native to South Africa where, however, it is now relatively rare because hundreds of specimens were dug up by collectors in the past. It was first brought to Europe in 1897. Spurges are extraordinarily diverse plants and their number includes both annual and perennial species, as well as herbaceous and woody plants. Some, such as E. obesa, resemble cacti. The stem is unbranched, spherical, 8-12 cm (3-5 in) across and divided into eight broad ribs. The entire stem is pale green to grey-green, with transverse purplish-red stripes. Small flowers arranged in a cyathium – the inflorescence characteristic of spurges – grow from a slight depression in the crown. When bruised all spurges exude a bitter milky sap.

Throughout the year it requires lots of light, and, in summer, sun and warmth. The growth period is in autumn. Water with care. Propagate from seed, which germinates rapidly and well, or by offshoots.

Euphorbia milii-splendens ‘Lutea’

Crown of Thorns is a very spiny shrub with succulent, branched stems. It is native to Madagascar, but has spread from there and became established in several tropical regions. The spines may be up to 1.5 cm long, are obovate, wedge-shaped at the base and completely glabrous. The inflor escences (cyathiums), composed of tiny inconspicuous flowers, are enclosed by two large, yellowish bracts. In the more commonly grown type species, the bracts are a vivid red.

This spurge is a lovely and thriving house plant. It grows extremely well in houses with central heating. It requires a sunny location throughout the year, preferably in a window. It grows best in a mixture of compost and sand. Water liberally during the growing period, but limit watering during the rest period from November to February, and again for about a month after the flowers have faded. Propagate by cutting off the tip of the stem, letting the milky sap that oozes out dry up and then inserting it in compost.