Fockea or commonly called water root is a genus of erect or twining perennials growing from tuberous rootstocks. They form part of the Apocynaceae, dogbane or milkweed family.
The subterranean or sometimes partly exposed caudices or tubers become very large on the old plants of some species, sometimes nearly 50 kg, which may come as a surprise, for the plants may be quite inconspicuous in the veld. Some of the species may produce plants that become older than 200 years.
The tubers mostly consist of spongy tissue that collects water during the rainy season for sustaining the plants during drought. The milky latex exuded by plant parts is toxic in at least some species.
The leaves grow from branching stems that straggle, twine or are erect, emerging from the caudices. The simple, opposite leaves are sessile or short-petioled with entire margins. The leaf-shape is elliptic or linear, the blades sometimes undulating. The plants may be dry season or dry period deciduous.
The inflorescences are small, axillary clusters or cymes of bisexual flowers, in some species inconspicuous. The calyces have lobes or sepals shorter than the corolla tubes. The bell-shaped corolla tubes end in lance-shaped or thread-like lobes that are longer than their tubes. Flower colours include white, green, yellow and brown.
Tubular coronas arise from the centre of the corolla cup bases, longer than the staminal columns positioned inside them. There are variously shaped teeth on the corona upper margins. The anthers have two locules each and membranous appendages. The pollinias or pollen masses are erect, attached to the pollen carrying glands. Each style ends in two small lobes.
The fruits are spindle-shaped follicles tapering to their tips. The seeds are obovate or elliptic, somewhat flat with wings on their margins.
There are six Fockea species, all in tropical Africa south of the equator and southern Africa, where they are widespread in arid regions, often where temperature extremes occur.
Fockea is named after a Dutch botanist Charles Focke.
Fockea caudices have been consumed as human food (and drink) in ancient times and also more recently used by the Khoi and the San. The toxic latex is said to be neutralised by prolonged cooking, although some species have been eaten raw or roasted. Care should be taken! Fockea jam has been mentioned. The plants are popular in horticulture.
None of the five species occurring in South Africa is considered to be threatened in its habitat early in the twenty first century.
The plant in picture is Fockea capensis (Leistner, (Ed.), 2000; Vlok and Schutte-Vlok, 2015; Wikipedia; https://worldofsucculents.com; https://hscactus.org; http://redlist.sanbi.org).