Hoodia gordonii: Natural History
Although it looks like a cactus in outward appearance, Hoodia gordonii is actually a succulent and a member of the Asclepiadaceae "Milkweed" subamily. The plant has a clumping aspect and spike-like stems that are generally the size and shape of a cucumber but covered in numerous lateral lines of sharp spines.
From seed the plant grows as a single stem, but this soon starts branching at the base and mature plants can have as many as 50 individual branches and weigh as much as 30 kg. Under ideal conditions in their native Kalahari environment plants can attain a maximum height of 1m (though this is rare).
Hoodia gordonii flowers once a year after the seasonal rains. The flowers themselves are large compared with the size of the plant and are borne near the apex (top) of the stem. Each stem may bear as many as three flowers and in a good season the entire plant may be covered with pinkish trumpets. The flowers themselves have a carrion-like smell (smell similar to rotten meat) and are used to attrct carrion insects to pollinate them. In colour the flowers can vary from pale straw to dark maroon and are normally bourne in August or September (Southern Hemisphere winter). Seed is produced in October or November and the tiny seed capsules resemble small antelope horns (hence their common name in Afrikaans of bokhorings).
Hoodia gordonii Distrubution
Despite being a rare plant, Hoodia gordonii actually has a fairly wide geographic distribution extending from the northeastern part of the Western Cape of South Africa, northwestern regions of the Northern Cape and southern Namibia as well as Botswana. It is also tolerant of extreme temperature conditions, capable of surviving above 40°C and tolerant of temperatures down to -3°C for short periods. The plant is also tolerant of widely-differing growing conditions and in the wild can be found in deep Kalahari sands, on dry stony slopes or flats and under the protection of xerophytic bushes.
Hoodia gordonii Derivation of the Name
Hoodia gordonii was 'discovered' by Col. RF Gordon in December 1778 in the Upington area of South Africa in honour of this Francis Masson, a famous botanist, named this plant Stapelia gordonii. In 1830 the genus was later transferred by Sweet into the genus Hoodia, which was named in honour of van Hood, a keen succulent grower. Common names for this plant include: bobbejaanghaap, bergghaap, bitterghaap, bokhorings (Afr.); Khobab (Khoi); Xhoba (Kung); Queen of the Namib; Bushman's Hat.
Propagation of Hoodia gordonii.
Propagation of this plant is mainly done from seeds (in that cuttings don't generally produce a basal callous from which roots can form). The seed horns must be semi-dry and starting to split down the middle before seed can be collected. The seeds themselves are light brown in colour, are flat and have a pappus of fluffy hair attached to their one end. This acts as a kind of parachute when the seed pod splits open. The seeds are blown some distance from the parent plant where they will establish themselves. Because of the popularity of Hoodia as a medicinal plant, trade in seeds is booming and Hoodia farms have been established in Mexico, South America, the southerns states of the US and China.
Hoodia realy needs high temperatures 28°C or above and very low rainfall to thrive and germination will only occur above 18°C in semi-dry conditions. Though once established the plant will grow well at temperatures of 10°C and above. The growing conditions also seem to affect the quantity of the active chemical, p57 produced by the plant. The plant is also tolerant of very differing lighting conditions and can survive in semi-shade (full sunlight only in the morning and evening) or in direct sun.