|Etymology - From the Greek words gymnos, meaning "naked" and kalyx, meaning "bud".
It is fairly easy to place an unknown cactus into the genus Gymnocalycium especially with a flower bud. Choosing the species is another matter. The majority of species in this genus consist of globose, solitary plants with ribs that are often only somewhat tuberculate. This slight punctuation along the ribs results in a "chin-like" appearance and this characteristic has earned it the nick-name "Chin Cactus". In general, each areole has a handful of proportionately-sized spines. Of course, there are exceptions of clumping, strongly tuberculate, or heavily-spined species, but in these cases flower buds will ensure that even these plants belong in Gymnocalycium.
These flowers are defined as being "naked", that is, without any spines, wool, or bristles. In all species, they are smooth and scaled. Someone resembling the tip of young asparagus shoots. Nearly all species have white, cream-colored or pale-pink flowers, while a few have dark red or yellow. Flower size is moderate among cacti and typically flowers are 1 to 1.5 inches (2.5 to 3cm) wide. While flowers come easy and at an early age on Gymnocalycium plants, they usually need high-heat to open fully and thus do much better in a greenhouse for those outside Arizona!
The largest of this genus may attain to around 7 inches (16cm) high and 12 inches (30cm) in diameter, while most species stay well under 5 inches (13cm) in height and diameter. This small size and relatively easy care requirements make this genus very popular in cultivation. Among the most popular is the red-flowered, G. baldianum and the unusually colored G. mihanovichii. The latter of these is even more popular as a grafted mutation of either variegated or chlorophyll-lacking, bright red plants incapable of surviving on their own roots. In fact, these might be one of the most prolific plants in cultivation as they are sold in large retail outlets as a novelty with the name "Lollipop Cactus".
In habitat, this species occurs in South-Eastern South America in various environs and elevations.