Origin and Habitat: Somalia.
Altitude range: 600 – 750 m.
Habitat: Grows on stony hill slopes on gypsum outcrops.

• Euphorbia ponderosa S.Carter

Description: It is a beautiful spiny perennial succulent that forms a densely branched, compact cushions of up to 30 cm in height and in diameter.
Stem: It has a short 7-angled and stout central stem that soon branches at its top. Branches, thick, terete, grey-green 1-2,5 cm in diameter, covered with raised tubercles 4–8 mm apart in 5 to 8 spiral series.
Root: Fibrous
Spine shield: rounded-obovate, 3-6 mm long 2-5 mm wide.
Spines: Very different in young and mature specimens, juvenile specimens have 4 vestigial, relatively dense and thin spines with an attractive design, while the adult specimens produce only a pair of stout, opposite, stipular spines up to 12 mm long (but usually shorter).
Inflorescence: Solitary cymes, 1-forked, with peduncle and cyme-branches 1.5 mm long.
Flowers: Cyathia in groups of three 1 mm above the the spine-shields, 3 mm in diameter. Glands 1,3 mm broad, yellowish, not touching. Ovary pedicellate. Styles 2 mm long.
Fruit: Capsules on a recurved pedicel to 6 mm long.

Cultivation and Propagation: This specie has the fame to be quite tricky to cultivate. A very very light and warm place in full sun is highly appreciated. It does best in a mineral soil, good drainage is essential. Water sparingly during the summer months and keep dry in winter. In the short growing season it likes ample water and in this period it grows rather quickly, though not for a long time. When not in growth it is killed right away, when given too much water. It is a slow growing long lived plant and once established, it will be content in its position and with its soil for years. It can tolerate moderate shade, and a plant that has been growing in shade should be slowly hardened off before placing it in full sun as the plant will be severely scorched if moved too suddenly from shade into sun.
Frost Tolerance: Tender, it needs frost protection. Recommended minimum temperature is 12 °C or even above.
Propagation: It is propagated from seed sown during spring or summer. Sowing seed of this species is the surest method of growing typical offspring and seedlings are in the first season relatively easy to grow but as seedlings age they are difficult to keep alive. It can be reproduced by cuttings or grafting as well but often lateral branches fail to produce the characteristic thick main stem. Seedlings are best grown grafted to accelerate growth and to increase survival rates of the seedlings.
Grafting: The plants that are grafted on a more vigorous and easier stocks are easier to keep alive, grow faster and produce more flowers and seeds. The method of grafting euphorbias differs little from that of other succulents, except in one important aspect. The latex must be washed or sprayed off until hardly anything remains. After the latex flow has stopped, a further 1-2 mm slice can be taken from both surfaces without a new latex flow starting. Both scion and stock need to be at the start of the growing season. The stock should be cut as near as possible to the growing tip, as here the vascular bundles are dense and not yet woody and will feed the scion in the best possible way. Where possible stock and scion should be of similar diameter. The cut surfaces are held together with elastic bands in cross style, over the plant top and under the pot. The plants should be left in an airy and shady place for 7-10 days before the bands are removed.
Warning: As with all other Euphorbias when a plant get damaged it exudes a thick white milky sap known as latex. This latex is poisonous and particularly dangerous for the eyes, skin and mucous membranes. So pay extreme attention not to get any in your eyes or mouth. Cultivated plants must be handled carefully.