globose depressed, up to 13cm
greyish-brown to blue-green (rather variable in colour in
cultivation, and in some specimens it is almost blue-black). The
9 to 10 broad
ribs are divided by deep grooves into
Areoles : deep-set
5 to 7 thin radial spines
that are straight or curved toward the stem, short, curved, pale
brown or grey, tinged with red at the base.
on the crown,
measuring 3 to 4 cm in length and the same across, open wide in
sunlight, and commonly of a most rich purple-red colour,
sometimes pinkish-purple (but also white, pink or orange). The
stamens are purple, the
anthers and the 6
stigma whitish yellow. This plant blooms in early summer
when it is only 2.5 cm. It is fast growing and can bloom one year
after being sown.
ovary is green, long and
dehisces (splits) down its length.
The synonym name Gymnocalycium venturianum is very common
and even at cactus nurseries. It is a very variable
species in its general appearance.
also many hybrids with a wide range of flower colours.