Euphorbia officinarum L.
Eng.: Spurge. Spa.: Cardón monillo. Fre.: Euphorbe oursin. Ara.: Darhmus. Tam.: Tikiut.
Monoecious shrub, fleshy, cactiform, up to 1.5 m in height or even taller in favourable soil and climate conditions. Overall shape generally hemispherical, with erect stems, usually less than 1.5 m in diameter. Stems ramose, usually shorter than the branches, star-shaped in cross section, with 5-10 angles. Stipular spines strong, rigid, 2-20 mm; arranged in pairs at the angles, born in an oblong-linear decurrent bud which forms a continuous line along the angle. Leaves reduced to tiny tubercles located on the spines. Inflorescences ± pedunculate, with 1-5 cyathia, positioned on the upper half of the branches. Lateral cyathia hermaphrodite; central cyathium usually male, that generally matures and falls off before the lateral cyathia. The cyathium as a whole is yellow to red-purple depending on the subspecies. Fruit a capsule (2.5-5 × 2.2-4 mm), subglobose, with pedicel green to red-purplish. Cocci clearly marked, glabrous, smooth or finely punctate, green or red-purple, but always with a deep purple keel. Each coccus contains a seed, variable in size depending on the subspecies, with a wrinkled, whitish, yellowish or greyish surface; without caruncula.
Flowering:
June to November.
Fruiting:
August to December.
Habitat:
Very diverse terrains at low and medium altitude, from sea level to 1,900 m, in Saharan to semiarid bioclimates, but with a relatively high atmospheric humidity due to influence from the ocean.
Distribution:
Endemic to NW Africa, from SW Morocco (coastal regions of the High Atlas, Sus, western Anti-Atlas) to Mauritania.
Observations:
There are 2 subspecies which traditionally have been separated at a specific level. On one hand, E. officinarum subsp. officinarum [E. officinarum subsp. beaumierana (Hook.f. & Coss.) Vindt, E. beaumierana Hook.f. & Coss.] a sparse subshrub with spaced branches, with 7-10(13) sides, short spines (2-15 mm), cyathia and capsules sessile or subsessile, greenish; endemic to SW Morocco. On the other hand, E. officinarum subsp. echinus (Hook.f. & Coss.) Vindt (E. echinus Hook.f. & Coss.) which is a very dense subshrub, with tightly arranged branches of only 5-8 sides, longer spines (5-20 mm), cyathia and capsules short but distinctly pedunculate, slightly smaller, usually fully red-purple; with a much wider distribution, growing in semidesert areas: its northern boundary is the Sus River reaching Mauritania towards the S.
Conservation status:
A common and locally abundant species. It is not considered threatened. Currently, it has not been assessed at a global level in the IUCN Red List of Threatened Species. In the Livre Rouge de la flore vasculaire du Maroc (Fennane, 2021) the subspecies officinarum has been considered as Vulnerable (VU) and the subspecies echinus as Near Threatened (NT). Cactiform euphorbias are included in Annex II of CITES.