Publication: Sp. Pl. 451 1753
Description
Euphorbia officinarum is tufted monoecious succulent shrub 1-1.5 metres tall, with erect prickly, stems branching from the base but shorter than those of the Euphorbia resinifera. This species appears to be variable regarding the length of stems and number of ribs in different populations.
Stem: Main stem (trunk) often shorter than the branches. Branches 6 - 8 cm in diameter, up to 1 m tall and sparsely branched above, the younger branches are starry in section, with 9- to -13 deep ± straight angles, which become nearly obsolete as the plant advances in age. The stem abound in a milky acrid juice which corrodes the skin wherever it comes in contact with it.
Spines shield: Elongated, joined in a horny margin forming a continuous line along the angle.
Stipular spines: Strong, rigid, arranged in pairs on the angles, spreading, c. 5-15 mm long.
Leaves: The leaves are reduced to tiny tubercles located on thorns.
Flowers (cyathia): Simple, usually solitary (sometime up to 5) on sessile or shortly pedunculate cymes arranged in the upper half of the branches. Lateral cyathia hermaphrodites. Central cyathium usually male, usually maturing and falling off before lateral ones. Nectar-glands five red. The cyathium may be yellow to red-purple, depending on the subspecies.
Phenology: It blooms from summer to autumn and fruits from the end of summer and throughout the autumn.
Fruits: Subglobular, obtusely lobed 2.5-5 x 2.2-4 mm hairless, smooth or finely stippled, green or red-purple, but always with a deep purple keel. Peduncle long, reflexed greenish to reddish-purple.
Seeds: One per capsule variable in size depending on the subspecies, coarsely wrinkled whitish, yellowish or greyish; no caruncled.
Origin and Habitat
Mauritania, Western Sahara, Morocco, Algeria.
Altitude range: It grows at low and medium altitude, from sea level to 1900 metres above sea level.
Habitat and origin: It grows in different kinds of arid environment, but often with relatively high atmospheric humidity due to oceanic influence.