Xerophyte

Seeds

There are few dark brown seeds (22-37) in each fruits.

Note

The epithet 'calvescens' stands for ‘without spines’.

Flowers

35 mm wide, 23 mm long, with a red throat, the tepals are yellowish-white with a characteristic silky shine (almost pure white in Brazilian forms), the style is yellowish-white, with brownish-red or dark purple stigma lobes. The filaments are purple, and the anthers are golden yellow. The Brazilan form of N. calvescens has nearly white flowers with red throat.

Spines

Supination develops only on young plants, radial spines 3 to 6, thin, white, 2-5 mm long, central spines are not present. At maturity the plant ceases to produce spines.

Ribs

13-17, later to 21, initially well outlined and somewhat angled, later almost completely reshaped in round bumps

Stem

Solitary, flattened spherical, up to 14 (-20) cm wide, in habitat protruding only 1 cm from the ground (often hemispherical and slightly higher in cultivation), the lower part of the body extends into a long spherical root.

Fruits

Very small, initially whitish, 5-7 mm long, later red and extending to a length of 12 mm.