Plant Highlight: Gasteria rawlinsonii
By Brian Kemble
Gasteria is a modest-sized genus in the Asphodelaceae, related to the large genus Aloe. All the Gasteria species occur in South Africa, with a couple of them found also in neighboring countries. While most of these are stemless, this is not true of a unique cliff-dwelling species named Gasteria rawlinsonii.
The home range of Gasteria rawlinsonii is one valley named Baviaanskloof (Baboon Valley) at the western end of South Africa’s Eastern Cape Province. On the sides of the valley are narrow slot canyons, and it is on the vertical walls of these that the plants occur, getting direct sun for only a short part of the day.
About the Plant
Some populations of G. rawlinsonii have a distichous leaf arrangement (that is, the leaves are all in one plane, stacked one above the other on either side of the stem), while in other populations the leaves are whorled, in the manner of a spiral staircase. Plants of either sort develop long pendent stems which can in age become several feet long (over 1 m), and they offset at the base to form clumps. The leaves are succulent and tongue-like, up to 4⅓ inches long (11 cm) and an inch wide (2.5 cm), but usually less than this. Their color is dull green, olive-green or yellowish-green, often with a brownish tinge if given some sun exposure. The leaf surface is minutely roughened rather than smooth. Often the leaves are unspotted, but sometimes there are scattered whitish spots (if present, these are typically more evident on newer leaves, and faint on older ones). The leaf margins may be unarmed, but frequently there are tiny prickly teeth, which may be irregularly spaced (or present on part of the margin, but absent on another part).
About the Inflorescence
Spring is the main flowering time for G. rawlinsonii, with September and October being the principal flowering months in its Southern Hemisphere home. At the Ruth Bancroft Garden, the peak flowering time is April to early May. However, it is not exceptional to have a plant produce flowers at other times of the year. The inflorescence is unbranched and on the short side (most often between 4 and 12 inches long, or 10 to 30 cm, but occasionally longer than this). A smaller inflorescence may have only 10 or 12 flowers, while a larger one may have 30 or 40.
As is typical with Gasteria species, the flowers of G. rawlinsonii are shaped like commas and dangle from the flowering stem. The pedicels (the stalks of the individual flowers) are slender and about .4 inch long (10 mm). The flower length varies from .63 inch to one inch (16 to 25 mm), and the pot-bellied basal half is coral-pink to coral-red, while the tubular remainder of the flower is striped with off-white and dull green (or grayish-green). On some plants the green of the stripes is replaced with coral-gray. There is a distinct groove down one side of the flower (the side cupped by the curve of the “comma”), an unusual trait in Gasteria.
About the Fruit
A successfully pollinated flower produces an elongated-oval capsule about .7 inch long (18 mm). Within are three chambers holding stacks of flake-like black seeds. After about two months or less, the capsule matures and dries, and at this point it splits open to release the seeds.
Care and Maintenance
Gasteria rawlinsonii is not difficult to cultivate in the home garden, though it is slow-growing. It does well in a pot, which can be placed on a shelf or atop a wall, so that the stem can have room to hang down as it elongates. Dappled sun, morning sun, or bright shade suits it well. It is interesting to note that propagation from leaves is common with gasterias in general, but G. rawlinsonii is an exception to this, since it is difficult to root leaves.
Click here to find out more about what’s in bloom at the Garden.