Fockea is a small genus of six accepted species of succulent shrubs and climbers belonging to the subfamily Asclepiadoideae (milkweeds) within the dogbane family Apocynaceae, order Gentianales. The genus is native exclusively to Africa south of the equator, with most species confined to southern Africa's arid and semi-arid zones.
The defining characteristic of most Fockea species is a bulbous, largely subterranean caudex — popularly called a "water root" — that stores water and nutrients and can reach impressive proportions. In Fockea capensis, the type species, the turnip-shaped tuber has been recorded at up to 3 metres in diameter. The caudex is edible in at least some species and has traditionally been used as a water and food source.
The genus was formally established in 1838 by the Austrian botanist Stephan Ladislaus Endlicher, based on a specimen of Fockea capensis collected in Cape Colony around 1786 by Franz Boos and Georg Scholl and cultivated at the Schönbrunn Garden in Vienna. One specimen from that original collection — known as the "Old Lady of Schönbrunn" — was still being cultivated in 1988, over 200 years after it was first collected, making it the oldest known potted succulent in cultivation.
Of the six species, four are endemic to southern Africa and form a tight clade. Fockea angustifolia, a tuberous climber ranging from Southeast Kenya to South Africa, is sister to those four. Fockea multiflora is the most distinctive member: a large, exclusively tropical liana lacking a tuber entirely, distributed from Tanzania to northern Namibia, and considered sister to all other species in the genus.
Etymology
The genus name Fockea honours Gustav Woldemar Focke (1789–1848), a German physician and naturalist best known as the author of De respiratione vegetabilium ("Of the respiration of vegetables"). The genus was named by Austrian botanist Stephan Ladislaus Endlicher when he described it in 1838.
Distribution
Fockea is endemic to Africa south of the equator. The four southern African species are confined to arid and semi-arid biomes of South Africa and Namibia, including the Cape Provinces and Namib fringe. Fockea angustifolia extends northward through southern and southeastern Africa to Kenya, while Fockea multiflora, a tropical liana, ranges from Tanzania to northern Namibia.
Taxonomy Notes
The genus Fockea Endl. (1838) is placed in the subfamily Asclepiadoideae of Apocynaceae (order Gentianales). Phylogenetic analysis supports Fockea multiflora — the only non-tuberous, liana-forming species — as sister to the remaining five species, with Fockea angustifolia sister to the four southern African endemics. The type species is Fockea capensis.
Cultivation
Most cultivated Fockea are grown as caudiciform ornamentals, prized for their swollen caudex. Fockea edulis and Fockea capensis are the most commonly encountered in cultivation. The "Old Lady of Schönbrunn" — a Fockea capensis specimen collected around 1786 — remained in cultivation at Schönbrunn Garden for over two centuries, demonstrating the genus's exceptional longevity under cultivation.
