Gasteria

Genus of succulent flowering plants from South Africa
Automatic taxobox
|taxon = Gasteria
|image = Gasteria pillansii var pillansii 1. jpg
|image caption=Gasteria pillansii
|authority = Duval
|display parents = 2
|synonyms ref=

The genus is named for its stomach shaped flowers ("gaster" is greek for "stomach") that result from the swollen base on the corolla. Common names include ox tongue, cow tongue, lawyer's tongue and, occasionally, mother in law's tongue.

Gasterias are recognisable from their thick, hard, succulent "tongue shaped" leaves. These are either in two opposite ranks (distichous), or in various distinctive spiral arrangements. Their inflorescence is also unique, with their curved, stomach shaped flowers, which hang from inclined racemes.

The species of this genus are mostly native to the Eastern Cape Province, South Africa, where the bulk of the species occur – especially in the small area between Makhanda and Uniondale which enjoys rainfall throughout the year. However, the distribution of several species extends widely across the low altitude coastal regions of the country, in an arched horseshoe shape across South Africa. At the one end of the genus's distribution, a species, Gasteria pillansii, extends into the far south west corner of Namibia. At the other end, a species reaches the Lebombo mountains of Eswatini.

Gasteria is part of the family Asphodelaceae, subfamily Asphodeloideae. Closely related genera include Aloe and Haworthia, and the species of these genera are known to hybridise relatively easily with each other. Dividing Gasteria into species is extremely difficult, as each plant can be highly variable. One plant will look different depending on its location, its soil and its age. Young Gasteria plants typically look entirely different from older specimens. Usually, young plants have flat, strap shaped, highly tubercled leaves, in a distichous formation. In addition, the species tend to flow into each other in gradual transitions, with many intermediate forms, rather than being cleanly divided into discrete and separate species. Lastly, hybrids occur easily and naturally, whenever the range of two species overlap in habitat. There is therefore considerable disagreement on how many species exist, with as many as 100 names being listed.

Species with distichous (two ranked), strap shaped leaves which are usually without keels.

Species generally form rosettes, with leaves usually bearing marginiform keels.

Gasteria species are grown in well drained, sandy soils in light shade. The species can all be propagated by off sets and cuttings (leaf cuttings can usually be rooted easily). They are also commonly propagated by seed. Germination usually occurs within 8 days but may take as long as one month depending on the species. Flowering times vary between species, but is usually in the spring & summer. Those in the summer rainfall areas to the east, tend to always flower in spring to summer (October–January in South Africa) such as Gasteria batesiana, Gasteria croucheri & Gasteria acinacifolia. Those in the areas which receive rainfall all year, usually flower also in later summer (December–January) such as Gasteria excelsa, Gasteria nitida, Gasteria vlokii and Gasteria brachyphylla var. bayeri. Others in this region flower all year, but with a peak in the spring, such as Gasteria rawlinsonii, Gasteria bicolor & Gasteria carinata. The westernmost species vary in their flowering times, within the species. Gasteria pillansii in the far west, flowers in summer (December–January), except for its northernmost variety "var. ernesti ruschii" which flowers in autumn (March–April). Gasteria disticha usually flowers in spring, but in the far north of its range near Beaufort West it flowers in December. Gasteria species are prone to Fusarium root rot, if they are over watered. The cultivar 'Little Warty' is a recipient of the Royal Horticultural Society's Award of Garden Merit. Several hybrids with species in other related genera have been created in cultivation, such as between Gasteria and Aloe (× Gasteraloe), and between Gasteria and Haworthia (×Gasterhaworthia).