The genus Gasteria belongs to the subfamily Asphodeloideae of the family Xanthorrhoeaceae. There are about 22 naturally occurring species, which are far less popular than species from the closely related genus Aloe.
Gasterias are native to South Africa, with one exception, the range of Gasteria pillansii is said to extend to Namibia.
For windowsill care, many cultivars are available. Some with green-yellow, green-white or knobbed leaves. Multi-generic hybrids, crosses of Gasteria with Haworthia or Aloe species, are also obtainable.
These hybrids are botanically named ×Gasteraloe (Gasteria & Aloe), ×Gasterhaworthia, or ×Gasterworthia (Gasteria & Haworthia).