Xerophyte

Seeds

Helmet-shaped, about 1.5-2 mm long and 1.5-1.9 mm wide, brilliant-black, more thin towards hilum, with unevenly distributed papilliform tubercles.

Roots

Consisting of 2-3 woody, long, main roots, branched distally in a network of thin fibrous roots.

Cephalium

Cylindrical, 7-13 across at the base, up to 9 cm tall, with creamy-white to greyish woolly hairs and, reddish to black black bristle protruding to 2,5-3(-5) cm above the wool.

Flowers

Buds lemon-yellow to white. Flowers nocturnal, funnel shaped up to 60 mm long and 40 mm wide. Pericacarpel 13 mm long, 5 mm wide nacked, white. Receptacle tubular up to 40-50 mm long, about 7-10 mm in breadth, with small lanceolate scales up to 4 mm long, 1-2 mm in width, yellowish, very pulpy, especially lower scales. Perianth segments in 3-4 whorls, inner ones lanceolate to 27 mm long and 4-7 mm broad, leathery, thin, white and the margin entire, outer perianth segments, lanceolate or spatulate to 25-33 mm long, 3 mm wide fleshy white, sometimes with a yellowish vein, and yellowish, especially on the lower side. Nectar camber tubular, 13-20 mm long, 2-7 mm across. Primary filaments variable in lengths from flower to flower from 2 to 7 mm long. Secondary stamens about 2.5-4 mm long in 10-14 whorls; anthers pale yellowish to golden yellow 1 mm long, 0.8 mm wide. Style creamy-white, about 20-30 mm long and 1 mm thick, stigma lobes 4-5, less than 4 mm in length, tapered upwards, slightly spreading white. The position of the stigma is at the primary stamens. The flowers are fragrant.

Spines

Black-grey or black, turning a dark-grey as they age, roundish to somewhat flattened in older specimens.

Ribs

Vertical, 15-20 (rarely up to 32), 1-3 cm tall, 3,5-4(-5) cm wide at the base, rounded, sometimes with a constriction between the areoles so that the groove between the ribs appears to be wavy.

Stem

Always single, flatted globular to globular, to 24(-35) cm in diameter, 7-8(-15) cm high (without Cephalium), greenish to green. The seedlings in the first two years, are purple.

Radial Spines

3-5 (rarely to 10), slightly curved inwards. The lowest one 3,5-4 cm long and 4 mm thick, the lateral pair directed obliquely downwards, up to 3 cm long and 3 mm thick at the base, and a second pair (if present) directed obliquely upward up to 2 cm long and 1,5 mm thick. Sometimes 1-3(-4) small spines (ca. 5 mm) pointing upwards, appears on the top of the areola.Central spine. Usually absent, occasionally in older specimens 1, up to 2 cm long and only near the cephalium. Plants with a central spine are very rare.

Fruits

White, 2 cm long and 1 cm wide.

Areoles

Approx 5-8(-12) per rib (in plants with cephalium), slightly sunken in the tubercles, round to oval (8-)10-12(-13) mm long, (4-)8-7(-9) mm wide, 2-3 cm apart, at first with a creamy or grey-white tomentum, later naked and black.