Fockea is a small but fascinating genus of the Apocynaceae family comprising 6 species, native to the dry, semi-arid regions of South Africa and Namibia — particularly the Karoo and Namaqualand biomes. Distinguished by their partially subterranean tuber, annual twining stems, and abundant white latex, Fockea species have earned a devoted following among collectors of caudiform succulents. Fockea edulis, with its edible tuber, is the most widely cultivated and the benchmark species for the genus worldwide.
Morphology
The defining feature of any Fockea is its tuber — a swollen, water-storing organ that may be flattened and disc-like, spherical, or irregularly lobed, partially buried in the soil with only its upper surface exposed. The texture of this tuber is smooth, often pale brown or grey, and the surface may be subtly bumpy or furrowed in older specimens as the tuber develops character with age. The tuber can reach impressive proportions in the wild: old specimens of F. edulis may attain a tuber diameter of 30–40 cm and weigh several kilograms.
From the tuber arise annual twining stems that grow vigorously during the warm months, reaching a metre or more in length. These stems bear opposite, glossy, dark green leaves with a leathery texture and a subtly wavy margin. Like all Apocynaceae, the plant produces an abundant white latex when cut — a characteristic of the family that is mildly irritant and should be kept away from eyes and open wounds. The flowers are small, cream or greenish-white, star-shaped, and borne in small axillary clusters; they are lightly scented. The fruit is a paired follicle typical of the Apocynaceae, containing seeds bearing a tuft of silky hairs that facilitate wind dispersal.
Key species
Fockea edulis — the most widely cultivated species, and the one from which the genus takes its popular reputation. Edulis means “edible”, referring to the fact that the large tuber of wild plants was traditionally consumed by Khoisan and other indigenous peoples of the Karoo as both a food and water source in times of drought. The tuber is indeed edible when cooked, though it is mildly bitter raw. In cultivation, F. edulis develops a satisfying, rounded to disc-shaped tuber relatively quickly, making it one of the more rewarding caudiciforms for growers willing to invest some patience.
Fockea capensis — native to the Western Cape of South Africa, producing a somewhat smaller tuber than F. edulis. The leaves are somewhat broader and the stems slightly less vigorous. It is less commonly cultivated than F. edulis but equally attractive as a specimen.
Fockea multiflora — as the name suggests, this species is noted for its more abundant flowering, producing small cream flowers more freely than its relatives. It is a slightly larger plant overall, with a more robustly developed tuber.
Fockea crispa — distinguished by its distinctly wavy or crisped leaf margins, which give the plant a somewhat different appearance from its relatives. Native to Namibia and adjacent South Africa, it is a somewhat more drought-adapted species, tolerating extended dry periods without difficulty.
Cultivation
Fockea are among the more accommodating caudiciforms in cultivation, tolerating a moderate range of conditions whilst still requiring the warm, bright, well-drained environment that all plants of arid southern Africa need. Full sun to bright indirect light suits all species; too much shade produces weak, elongated stems and poor tuber development. A free-draining substrate — a mix of grit, perlite, and cactus compost — is essential to prevent root and tuber rot.
Water generously during the active growing season, allowing the substrate to dry out between waterings. In autumn and winter, reduce watering significantly; the stems may be cut back to encourage a tidy dormancy period, though this is optional. A minimum winter temperature of 10°C is recommended; the plants are not frost-hardy. Repot every two to three years to refresh the substrate and encourage tuber development. Propagation is from seed, which germinates readily, or by careful division of established tubers — though the latter is rarely necessary and carries some risk.
The display position of the tuber is a matter of collector preference: displaying it raised above the soil surface — a practice known as “high-riding” — shows off the tuber’s form to best advantage but dries the roots more quickly and requires more attentive watering.