werdermannianus is a (usually) simple stemmed small cactus with
bright yellow flowers. This species shares some characteristics with
Stem: Globular to slightly cylindrical, often flattened up to 13
cm tall and 10 cm in diameter, yellowish-green to green.
Ribs: up to 40, vertical, straight rounded with many small
Areoles: White, wooly and closely set one to each other.
Radial spines: About 15-20, setaceous, more or less erected,
whitish or yellowish 4-5 mm long.
Central spines: 4-partite yellowish or reddish (N.
ferrugineus) acicular, sharp and flexible up to 15 mm long, the
lowest of them longer and pointing downward.
Flowers: About 6 cm long, up to 7 cm in diameter, pale yellow and
satiny. Tepals lanceolate darker at the tip, style quite long rich
egg-yellow coloured, stigma lobes10-12 carmine red.
Seeds: With distinctive longitudinally-oriented fine striate
forma mostruosa (Monstous form):
This plant is a rare oddity with areoles merging to form concentric
lines. The epidermis is harder than in the normal Notocactus and cracks
easily but this is not a defect and the plant will not suffer for this,
and also the fact that the body splits open
permits to the plant to develop original and strange shapes.