Among all the various growth forms in the genus Euphorbia, the design of this species stands out as something singular.
The plants consist of a thick main stem covered with numerous branches up to 8 cm long, decreasing in length towards the top of the plant.
In this way, a compact cone is formed up to 60 cm tall and to 25 cm across at base. In some cases however, the plants are not shaped quite so neatly, resulting in a far less appealing and peculiar habit of growth (see pictures).
The spines are in fact sterile flower stalks; they are 0.8 to 7 cm long and arise from both main stem and branches.
The species occurs on stony slopes and flats from Steinkopf in Namaqualand to the western Little Karoo.
One does not have to be a linguist to surmise that meloformis means shaped like a melon. Judging from the old synoniems pomiformis and pyriformis, the plants may also resemble an apple resp. a pear.
Usually the stems are single, more or less ball-shaped, to 10 cm tall and in diameter, with mostly 8 ribs and a depressed top.
The plants occur on gravelly flats in the Eastern Cape Province, mainly in and around Grahamstown, Uitenhage and the Coega area.
In ssp. valida (Euph. valida), the stem may become over 30 cm tall and 12.5 cm thick, with a rounded top and harder and more persistent peduncles.
Mature plants of this species usually have a globose caudex to 10 cm tall and to 9 cm in diameter. The branches are about a cm thick and normally about 1.8 cm long.
The species is very rare and only occurs between Calitzdorp and Oudtshoorn in the Little Karoo. It was described in 1999, but nowadays the consensus seems to be that it should be incorporated in E. decepta.
This species occurs in the western Karoo from Matjiesfontein to near Calvinia and is closely related to E. loricata and E. multifolia. (Peter Bruyns in “Plants of the Greater Cape Floristic Region”, published in 2013, even considers it a synonym of E. loricata).
The plants form rounded cushions to about 15 cm tall and to 30 cm or more in diameter, with many branches, which usually completely hide the main stem.
The 2-5 cm long white spines, which are in fact modified peduncles, are very obvious in the dry season; in winter and spring they are partly hidden by the up to 4 cm long leaves.
Plants belonging to this subspecies occur fairly widespread in northeast Uganda and northwest Kenya in sandy rocky soils, usually in the open at altitudes between 1075 and 1850 m.
They have a thick fleshy root with densely tufted, more or less round branches, which are 5-8 mm thick and erect to 15 cm tall or creeping to 50 (-100) cm long.
The branches bear tubercles to 2 cm apart in 4 series, with triangular spine shields 6 x 1.5 mm in size and spines 5-15 mm long; they differ considerably in colouring, from bright green often with darker longitudinal stripes to greyish-green with purplish stripes.
There is only one place in the world where this species is known to occur: Tanjona Vohimena, the southernmost tip of Madagascar*.
On this stark, wind-swept limestone terrace about 100 m above sea level, the species occupies an area of less than a km².
Old plants possess a large turnip-shaped root to 30 cm long and to 10 cm wide, topped by a densely branched crown to 30 cm in diameter. In habitat the branches creep along the ground as a result of the constant wind; in cultivation they are more or less erect.
The leaves form rosettes at the tips of the branches, they are to 25 x 8 mm in size and green to red-brown.
* The old name for this is Cap Sainte Marie, which explains the specific epithet.
Plant in cultivation; scanned slide