Xerophyte

Central Spines

None or rarely solitary and porrect.

Description

Discocactus tricornisSN|1433]]SN|1433]] is usually given as a synonym of Discocactus alteolens, which should have 5 or 6 radial spines instead of the 3 radial spines typical of D. tricornis. Possibly the plant bearing only 3 radial spines named D. tricornis is only a juvenile forms with fewer spines of the otherwise identical Discocactus placentiformisSN|1430]]. Nowadays this plant name is not accepted by botanists that treat it as synonym of Discocactus placentiformisSN|1430]], but it still has a value for a collector because they identify plants with particular characters. A tree spined “D. tricornis” has been commercialized by the cactus collector Karel Kníže (field number KK 668).

Flowers

Salverform; tube slender, bearing slender scales with naked axils; inner perianth-segments white, numerous, obtuse; ovary naked, glabrous.

Ribs

9 or 10, broad at base, low.

Stem

Solitary, broader than high, dull gray, crowned by a broad cephalium.

Radial Spines

Typically Discocactus alteolens has 5 or 6 radial spines (whereas Discocactus tricornisSN|1433]]SN|1433]] has mostly only 3), the 3 lowermost stout, one of which noticeably longer, bent downwards; the 2-3 upper ones (if present), very short, ascending.