Euphorbia unispina

Geographic & Climate

• Geographic Coordinates: West Africa to Central/East Africa (specifically spanning Guinea, Mali, Ivory Coast, Nigeria [Jos Plateau], east to South Sudan); type locality distribution core approx. 7°00'N to 12°00'N, 8°00'W to 10°00'E.

• Climate Classification: Tropical wet-and-dry / Savanna climate (Aw) and sub-arid tropical transitions.

• Habitat Characteristics: Altitude ranging from lowland up to 800 meters above sea level. Inhabits granite and granodiorite inselbergs, rocky hillsides, and open sub-arid savannas. Subject to distinct alternating wet and prolonged dry seasonal regimes with high ambient temperatures. Mineral-rich, highly porous rocky soil matrices.

Botanical Morphology

• Diagnostic Features: A stout succulent shrub reaching 2 to 4 meters tall in habitat. Features cylindrical, silvery-grey branches (1.6 to 2.5 cm thick) covered with shallow, polygonal tubercles (podaria) arranged in spiral lines. Stipules are modified into a single, stout, persistent pair of spines (6 to 10 mm long) per tubercle (giving the species its name). Large, fleshy, oblong to spoon-shaped leaves (5 to 12 cm long) grow in a tight rosette at the extreme tips of the branches during the active season, which are shed during dormancy leaving behind bud scales.

• Growth Habit: Summer-growing deciduous succulent. Slow-growing, upright candelabra-like branching habit. Goes completely dormant in autumn/winter, shedding leaves.

History & Etymology

• Etymology: The specific epithet unispina derives from the Latin prefix uni- (one) and spina (spine), directly referencing the characteristic single pair of spines emerging from each tubercle.

• Historical Context: Formally described by British botanist Nicholas Edward Brown. Historically noted across West African botanical surveys (such as those in Mali, Burkina Faso, and the Jos Plateau of Nigeria), it has long remained an elite rarity among specialized caudiciform and succulent collectors due to its unique prehistoric appearance and strict cultivation requirements.