All you wanted to know about Haworthias, Gasterias and Astrolobas: Astroloba bullulata

Astroloba bullulata, Varsbokkraal

Astroloba bullulata Uitewaal (L. Bolus)

by Jakub Jilemicky and Steven Molteno

bullulata: referring to the distinctive tubercles

A. bullulata is one of the most attractive of the genus, this species can be distinguished by its distinctive leaves which are short, compact, reddish, incurved (often twisted at an angle) and covered in “bullet-like” tubercles. One margin of each leaf ends before the leaf-tip; while the keel of each leaf becomes the margin (marginated keels). The dark tubercles and margins become pink, or even white, if exposed to extreme sun and heat. Bullulata is part of a complex of related Astroloba species, which form a graded spectrum, fading from one into the other. This includes the species Astroloba pentagona to the east, and the newly declared Astroloba cremnophila to the south.

Astroloba bullulata, Witteberge Valley

Like its closest relatives, this species flowers in the dry summer (mostly from November to January in habitat). Its inflorescence bears tiny, yellowish, tubular flowers, which are insect pollinated. In habitat it flowers every year, and the old dead inflorescence stems remain, allowing an observer to see and measure a given plant’s growth every year (by seeing the distance between each dried, remnant flower stem). One can also use this method to a certain extent, to determine age.

Flower detail of A. bullulata from Viskuil

This species occurs in the extreme south-western corner of the great Karoo. Its most western recorded locality is to the north-east of Ceres. It is common in the eastern part of the Tanqua Karoo, around Matjiesfontein and Laingsburg, and as far south as the Rooinek pass, where it gradually becomes Astroloba pentagona. It favours succulent karoo vegetation, usually in clay-rich soils, on rocky slopes and within protective bushes.

Map of distribution

Distinctive forms include an extremely short, compact form south-west of Laingsburg, and a massively robust, stocky form which appears erratically in many populations but is particularly common to the north of this species’ range. To the south-east of its natural range, as this species gradually fades into Astroloba pentagona, intermediate populations have stronger and stronger striations (stripes) and fewer and fewer tubercles.

Astroloba bullulata thrives in semi-shade environments, where it is provided with extremely well-drained soil, and minimal watering primarily in the winter. It can easily be propagated by seeds or by cuttings/offsets, but is relatively slow-growing.