Coryphantha cornifera (DC.) Lem.

Coryphantha daimonoceras Lem.

Origin and Habitat: The main distribution is in the Mexican states of Querétaro and Hidalgo, south to the Valle de Mexico, north to Guanajuato and sporadically in San Luis Potosí.
Habitat: Limestone gravel on low hills and plain.

Synonyms:

• Coryphantha cornifera (DC.) Lem.

Common Names include:
ENGLISH: Rhinoceros Cactus
SPANISH (Español): Biznaga-partida de Cuernos

 

Description: This is a very variable species, normally solitary, rarely sprouting.
Stem: Flat globose to cylindrical, up to 8-15 cm in diameter, 6-12 cm tall, dull olive-green, apex depressed, with a blunt, depressed apex covered with e wool.
Tubercles: Tubercles are spirally arranged in series of 5 and 8. Conical, rhomboid at the base, obliquely cut, grooved above; on new growth the groove may show some felt. Basal diameter 12-16 mm, 8-14 mm tall. Axil at first woolly, then naked.
Areoles: Oval, 3mm long, 2,5 mm wide (when central spines absent), round 2 mm Ø (when central spine present)
Radial spines: 10 to 20 fairly stout, pale whitish, yellow or horn-coluoured, sometimes darker tipped, 0.9-1.6 cm long, horizontal, irregularly radiating, interwoven, needle-like, straight or slightly curved; in youth pectinate. Occasionally 3-4 thinner spines, more densely set.
Central spines: 0 or 1( to 3), dark brown, becoming grey from the base, subulate. The dominant central is straight, porrect, or curved downward, usually about 1 cm long, but it may be longer on older plants (up to 1,8 cm); the other two protruding laterally, and curved.
Roots: Fibrous root or semi-taproot.
Flowers: Very big, 5-7 cm wide, yellow (occasionally red), funnel shaped, 6-7 cm. The linear segments are lemon-yellow, sometimes red at the base. Filaments reddish to reddish-yellow. Anthers yellow, stigma pale yellow, stigma lobes whitish.
Fruits: Green, juicy with attached flower remnants, 20-25 mm long, 10 mm wide.
Seeds: Reniform (kidney-shaped), brown, 1,3 mm long.

Coryphantha cornifera (llifle.com)

https://youtu.be/UuD4CLjBKGU?t=102