Xerophyte

Habit

Gymnocalycium guerkeanumSN|21396]]SN|21396]] is a small cactus species, usually solitary, but sometimes cespitose and barely rising above ground level.

Central Spines

Absent.

Description

Gymnocalycium guerkeanumSN|21396]]SN|21396]] is one of the yellow-flowering Gymnocalyciums which is now considered a local or morphological form of the widespread and very variable Gymnocalycium hyptiacanthum subs. uruguayense, it is also closely related to Gymnocalycium artigasSN|21398]]SN|21398]] and (possibly) Gymnocalycium laeanum and all these may well be the same species.

Flowers

Few at any one time near centre of plant, yellow or greenish-yellow, nearly as broad as long when expanded; inner perianth-segments narrowly oblong, acute, sometimes toothed; scales on the ovary acute.

Spines

All radial, usually 5, unequal, the longest 12 mm, long, yellowish, with brownish bases, rough, usually spreading or appressed.

Ribs

About 9 (or more), broad and obtuse, somewhat tuberculate.

Stem

Spherical or hemispherical, usually much depressed, 3-3,5(-8) cm tall, 5 (or more) cm in diameter, dull green.

Areoles

Orbicular, greyish tomentose when young.