If you watch closely how bulbous plants grow and how they look like, you will notice these two bulbs: Bowiea and Schizobasis. Both genera are members of the Hyacinthaceae family, are closely related and orginate both from Africa. The plants form at the beginning of the growing season a new stem which branches strongly. They don't form real leaves.
Bowiea
The genus Bowiea contains two species which are native to South Africa, Zimbabwe, Malawi, Zambia, and Tanzania. The genus is named in honour of J. Bowie (1789-1869), a British collector for Kew Gardens. Bowiea has a flattened true bulb which usually grows above the surface of the soil. The differences between the two species are the growing period and the colour and size of the flowers. Bowiea gariepensis is a winter-grower and has white,
relatively large flowers. The summer-grower B. volubilis has small, green flowers.
There has been some discussion about how many species Bowiea contains. For a long period it was considered that there was only one species: B. volubilis. This species had various 'growing forms'. A variation on this theory is that there should be a subspecies: ssp. gariepensis. Another opinion is that there two species: B. volubilis and Bowiea kilimandscharica. This last mentioned species grows only on ount Kilimanjaro in Kenya. The reason to consider it to be a species is the isolated growing area, apart from the other growing regions of B. volubilis.
Neither species is difficult to grow. During the growing season the stem, which can reach a length of one metre or more, needs support. The bulbs are sensitive to rot caused by too much water which can be avoided by planting the bulbs above the surface of the soil. Furthermore, the soil should consist of half sand/half compost and must be left to dry before watering again. The bulb of B. volubilis must not be placed in direct sunlight, especially not at the beginning of the growing season, as that will lead to growing disorders; the stem will not grow until the bulb is taken away from direct sunlight. Both species can be propagated by offsets or by seed. In the dormant period both Bowiea species are kept dry.
Schizobasis
Schizobasis is a genus of one species: S. intricata, which is native to South Africa. The true bulb has scales and usually produces one strongly branched stem. At the tip of each branch a flower is produced. The six tepals are green-white and reflexed. S. intricata is a summer-grower which flowers in the period June-August. The plant can easily be propagated by seed.
The plant is quite easy to grow, requires no special cultivation conditions and is resistant to most pests and diseases. During the dormant period the branched stem withers. Once every two to three years the bulb is transplanted into new soil. The bulb is planted partly above the soil level. When the stem is visible, watering is started. In October water is withheld again. If it is continued during the dormant period, the stem does not die off. The bulb is stored at a temperature of 8-15 ºC.
Literature
Bircher, C., C. Prentice, N. Crouch en R. Symmonds. Conservation concerns for Bowiea volubilis, an unusually succulent member of the Amaryllidaceae. Herbertia, 1998, (53), 81-89.
Van Jaarsveld, E. Bowiea gariepensis and B. volubilis. British Cactus and Succulent Journal, 1992, 10(4), 96-98.
Jessop, J.P. Studies in the bulbous Liliaceae in South Africa: 7. The taxanomy of Drimia and certain allied genera. Journal of South African Botany, 1977, 43 (4), 265-319.