All you wanted to know about Haworthias, Gasterias and Astrolobas: x Astrolista bicarinata

x Astrolista bicarinata, near Lemoenshoek

x Astrolista bicarinata (Haw.) Molteno & Figueiredo

by Jakub Jilemicky and Steven Molteno

Astrolista: A portmanteau of "Astroloba" and "Tulista" bicarinata: ("two-keeled") referring to the way some plants have several keels on their leaves

x Astrolista bicarinata is a variable natural hybrid that is formed by pollination between Tulista pumila and Astroloba corrugata in the overlap area between their ranges. It is not surprising that a hybrid population is unusually varied, but this entity can usually be identified in the field by its large size, by the large numbers of tiny tubercles that cover its leaves (often in longitudinal lines), and by its tall, branched inflorescence. The leaves are usually straight - sometimes incurved or recurved. They also usually have keels - sometimes several - and the flowers show some similarity to the flowers of Tulista pumila. They appear on an inflorescence that is usually branched.

Distribution map

This hybrid is commonly found wherever its two parent species grow in close proximity. There are many different forms which the hybrids take, ranging from some which appear more similar to their Tulista parent, to others which just look like extremely massive Astroloba corrugata. Most are somewhere in between. Even with such a variety at each locality, there is not much difference between different localities. You tend to find a similar range of forms at each locality.

x Astrolista bicarinata, Keurfontein, ex Karoo Botanic Gardens, photo by Steven Molteno

This hybrid has been known by a wide range of names in its confusing history. Some of them are still in use. Although "skinneri" is now formally recognised to be a synonym of "bicarinata", it is still sometimes used for some cultivars, though not with much consistency. Until the genus Haworthia was split, the hybrid's correct name was x Astroworthia bicarinata. However its one parent species is now in genus Tulista, not in the remnant genus Haworthia sensu stricto. So the name of the hybrid needed to be adapted. Otherwise the name would imply that one of its parents was a "soft-leafed Haworthia".

x Astrolista bicarinata, N of Ouberg Pass

x Astrolista bicarinata is fully fertile, and a great many cultivars have been created from its stock. The popular "Silver Horn" (Gintsuno) cultivar is possibly also a descendant of an x Astrolista bicarinata, judging by its vegetative and floral characters. It was first recorded in the 1960s in the succulent collection of Mr Hiroshi Hirao in Japan. It was sometimes confused with the natural species Astroloba tenax, which it does resemble in some ways. However "Silver Horn" has more erect, mat-surfaced, silver-coloured leaves. Most importantly, its flowers are typical of x Astrolista, and entirely unlike the grey flowers of A. tenax.

Known localities: