Common names: khadiwortel (Afr.)
The succulent plants of this genus have long been known as an additive to alcoholic fermentations, making them extra potent. It is the thick underground roots that are added to the brews. The plants make attractive rockery subjects, forming low, dense clumps with showy flowers.
The low , clumps with large, fibrous roots are characteristic of Khadia . The only exception is K. borealis , which has a creeping habit, long internodes and roots at the nodes. Leaves of all species are succulent, with sharp tips. In all but the above species the leaves are densely arranged. Flowers are white or shades of pink and are quite large and showy. The genus name is derived from its use as a potent additive to fermentations known as khadi . The fruits are capsules containing a varying number of locules (compartments).
Distribution and habitat
This mesemb genus comprising six species is confined to grassland or open woodland of the northern provinces of South Africa. This is unusual, as most other mesemb genera are found further south, the highest diversity being in the Succulent Karoo. Habitats where these species thrive are rocky spots with shallow soil in summer rainfall areas. Altitudes vary, but are generally above 1 400 m (Chesselet et al. 1998).
The rocky situations where these plants occur, ensure that little else can compete with them. They can withstand fire, as rocky places have low biomass and less organic material that can fan a fire. Leaves that are singed recover quickly.
Like most other mesembs, seeds are borne in capsules which open when wet (hydrochastic), closing again once they dry out. These capsules have been used as a taxonomic tool to separate the species.
In times of extreme drought, Khadia leaves are eaten by hares and insects but this seems to have little effect on the plants, as recovery is swift. Areas where these plants grow often receive frost in winter and in some parts of Mpumalanga snow occasionally falls at high altitude. The plants are, however, well adapted to withstand these temperature fluctuations.
The pollinators of Khadia species are unknown, as this aspect of their biology has not yet been studied.
Khadias are not very popular as garden plants. They have been used traditionally as a fermentation agent, but traditional brews containing these plants are becoming increasingly scarce.
Attractive garden plants when planted in the right setting, species of Khadia can be a colourful addition to a rockery. It forms a compact, low-growing clump, which increases in size with age . Plants like aloes or other succulents requiring similar growing conditions are recommended as companion plants. Soil should be well drained and porous, containing a good deal of humus. As Khadia is a summer rainfall genus, it should be watered very well in summer (southern hemisphere). Water very sparingly in winter.
The most attractive species is K. acutipetala as it has the largest flowers of the brightest pink hue, standing out in a rockery when flowering.
These plants make excellent potplants and are prized by succulentophiles for their compact nature and attractive flowers.
Recent studies (Knoll & Hankey 2003) have shown that Khadia beswickii can be propagated by rooting the leaves in a well-drained growth medium such as river sand mixed with peat-based potting soil. Most species of Khadia grow from seed and stem cuttings, but plants take quite long to reach a noticeable size when grown from seeds.
Some species are susceptible to leaf scale and this can even be seen in populations growing in the wild. Conditions that are too moist with insufficient air -flow can lead to red spider invasions, which are difficult to eradicate.
All six species in the genus are confined to summer rainfall areas in the northern provinces of South Africa.
K. acutipetala (N.E.Br.) N.E.Br. was the first species to be described and is also the type of the genus. This is the species most frequently used as an additive to alcoholic fermentations and it can be distinguished by its large, bright pink flowers. It is the mo