Gymnocalycium, commonly called chin cactus, is a genus of about 70 South American species of cactus. The genus name Gymnocalycium (from Greek, "naked calyx") refers to the flower buds bearing no hair or spines.
The species of the genus Gymnocalycium are low-growing, usually solitary or sometimes small cushion-forming plants with globose, depressed-globular to short-cylindrical stems. The 4 to 15 (rarely more) ribs are usually broadly rounded, often sinuous, occasionally warty, and often have a "chin" just below the areoles. The thorns are very variable.
The diurnal, funnel- or bell-shaped flowers appear at or near the apex. They are white or pink, sometimes yellow or bright red. The flower cup and the corolla are covered with a few large, broad and obtuse scales that have membranous edges. The areoles are bare. The perianth is usually spread.
The stamens form two circles. The first surrounds the nectar chamber, the second is attached near the opening of the corolla. The oblong to spherical fruits are dry or fleshy and spring up in various ways. A permanent flower residue adheres to them. The seeds are very variable. Their color ranges from brown to black, the size from quite small to relatively very large.
In cultivation they are popular for their easy flowering habits, and the flowers are generally brightly colored.[1]
Species of the genus Gymnocalycium according to Plants of the World Online :[2]
| Image | Scientific name | Distribution |
|---|---|---|
| Gymnocalycium affine | Argentina (Córdoba) | |
| Gymnocalycium alboareolatum | Argentina (La Rioja) | |
| Gymnocalycium alenae | Argentina (Córdoba) | |
| Gymnocalycium amerhauseri | Argentina (Córdoba) | |
| Gymnocalycium andreae | Argentina (Córdoba) | |
| Gymnocalycium angelae | Argentina (Corrientes) | |
| Gymnocalycium anisitsii | Bolivia to Paraguay | |
| Gymnocalycium × applanatum (G. capillense × G. ochoterenae) | Argentina (Córdoba) | |
| Gymnocalycium baldianum | Argentina. | |
| Gymnocalycium basiatrum | Argentina (La Rioja) | |
| Gymnocalycium bayrianum | Argentina (Salta, Tucumán) | |
| Gymnocalycium berchtii | Argentina (San Luis) | |
| Gymnocalycium bodenbenderianum | Argentina (to NW. Córdoba) | |
| Gymnocalycium bruchii | Argentina (San Luis, Córdoba) | |
| Gymnocalycium cabreraense | Paraguay | |
| Gymnocalycium calochlorum | Argentina (Córdoba) | |
| Gymnocalycium campestre | Argentina (Córdoba) | |
| Gymnocalycium capillense | Argentina (Córdoba, San Luis) | |
| Gymnocalycium castellanosii | Argentina (La Rioja, San Luis) | |
| Gymnocalycium chacoense | Bolivia (Santa Cruz) | |
| Gymnocalycium chiquitanum | Bolivia. | |
| Gymnocalycium denudatum | S. Brazil to Argentina (Misiones, Corrientes) | |
| Gymnocalycium erinaceum | Argentina (Córdoba) | |
| Gymnocalycium esperanzae | Argentina (La Rioja) | |
| Gymnocalycium eurypleurum | Paraguay | |
| Gymnocalycium gibbosum | Argentina. | |
| Gymnocalycium glaucum | Argentina. | |
| Gymnocalycium horstii | Brazil (Rio Grande do Sul). | |
| Gymnocalycium hossei | Argentina | |
| Gymnocalycium kieslingii | Argentina (La Rioja, Santiago del Estero). | |
| Gymnocalycium kroenleinii | Argentina (La Rioja). | |
| Gymnocalycium kuehhasii | Argentina (Córdoba). | |
| Gymnocalycium kulhanekii | Argentina (Córdoba) | |
| Gymnocalycium marekiorum | Bolivia (Santa Cruz) | |
| Gymnocalycium marsoneri | Argentina (to Chaco) | |
| Gymnocalycium mendozaense | Paraguay. | |
| Gymnocalycium mesopotamicum | Argentina (Corrientes) | |
| Gymnocalycium mihanovichii | Paraguay to Argentina (Chaco, Formosa) | |
| Gymnocalycium × momo (G. monvillei × G. mostii.) | Argentina (Córdoba) | |
| Gymnocalycium monvillei | Argentina (to Córdoba) | |
| Gymnocalycium mostii | Argentina (Córdoba) | |
| Gymnocalycium neuhuberi | Argentina (San Luis) | |
| Gymnocalycium nigriareolatum | Argentina (Catamarca, La Rioja) | |
| Gymnocalycium ochoterenae | Argentina (San Luis, Córdoba) | |
| Gymnocalycium oenanthemum | Argentina (Catamarca) | |
| Gymnocalycium paediophylum | Paraguay. | |
| Gymnocalycium paraguayense | Paraguay. | |
| Gymnocalycium pflanzii | Bolivia to Paraguay. | |
| Gymnocalycium pinalii | Argentina (Córdoba) | |
| Gymnocalycium ponomarevae | Argentina (Catamarca) | |
| Gymnocalycium quehlianum | Argentina (Córdoba). | |
| Gymnocalycium ragonesei | Argentina (Catamarca, Córdoba) | |
| Gymnocalycium reductum | Argentina (Buenos Aires) | |
| Gymnocalycium rhodantherum | Argentina (Salta, La Rioja, San Juan) | |
| Gymnocalycium ritterianum | Argentina (La Rioja). | |
| Gymnocalycium robustum | Argentina (Córdoba: near Quilino) | |
| Gymnocalycium saglionis | Argentina | |
| Gymnocalycium sanluisense | Argentina (San Luis). | |
| Gymnocalycium schickendantzii | Argentina (San Luis). | |
| Gymnocalycium schroederianum | Argentina to Uruguay. | |
| Gymnocalycium spegazzinii | Argentina. | |
| Gymnocalycium stenopleurum | SE. Bolivia to N. Paraguay. | |
| Gymnocalycium striglianum | Argentina (Mendoza, San Luis) | |
| Gymnocalycium taningaense | Argentina (San Luis, Córdoba) | |
| Gymnocalycium uebelmannianum | Argentina (La Rioja) | |
| Gymnocalycium uruguayense | S. Brazil to Uruguay | |
| Gymnocalycium victorii | Argentina (San Luis) | |
| Gymnocalycium volskyi | Uruguay | |
Their main area of distribution is Argentina, part of Uruguay, Paraguay, Bolivia and part of Brazil.[2]