(Pedalium or Sesame family)
50 species in 12 genera are found in tropical and southern Africa, Madagascar and Indo Malaysia.
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Cooper (1996) notes that this eastern African species bears burs with two short spikes that are liable to penetrate feet. Watt & Breyer-Brandwijk (1962) refer to the oval disc-like burs, which bear two stout spines that stand upright, as a hazard to animal feet.
The fruit, which is beset with large woody and barbed grapples about 5 cm long, can cripple a large animal by becoming jammed in the foot or in the hoof. It may also gain access to the mouth and firmly hook itself to the two jaws. This can lead to death by starvation (Watt & Breyer-Brandwijk 1962).
In the traditional medicine of southern Africa where the plant is found naturally, an ointment prepared from the fresh tuber is applied to all manner of sores, ulcers, boils, and other skin lesions (Watt & Breyer-Brandwijk 1962).
The spiny arms on the fruits resemble those found on Harpagophytum procumbens (see above) but are smaller (Midgley & Illing 2009).
[Information available but not yet included in database]
The plant is cultivated, especially in India, for the oil (sesame, ben or teel oil) from its seeds. The leaves, when steeped in water, produce a mucilaginous liquid that may be used in folk medicine as an external application in ophthalmic and cutaneous complaints (Wren 1975).
Cattle fed excessively on sesame meal develop eczema associated with loss of hair and itching (Steyn 1934, Watt & Breyer-Brandwijk 1962). Immediate (Type I) hypersensitivity reactions to sesame oil can occur (Batterman et al. 1958, Tornsey 1964). Sesame oil is used as a substitute for olive oil and other oils in cosmetic creams (Greenberg and Lester 1954) and in oleomargarine, iodized oil and cosmetics (Budavari 1996). Foods containing the oil were listed by Tornsey (1964).
Sesame oil, a constituent of an official zinc oxide liniment, was found to be the cause of contact dermatitis in 15/98 patients with leg ulcers for which the liniment was used. In one patient a positive patch test to crude oleic acid was observed as well as a positive patch test to sesame oil. As the patients did not react to peanut oil (Arachis) nor to olive oil (Olea) it was considered that triglycerides were not responsible for the dermatitis but rather the unsaponifiable fraction of the oil (which constitutes about 2% of the oil). This fraction contains sesamol, sesamolin and sesamin (Van Dijk et al. 1972, 1973).
In 100 cases of leg ulcers, 11 of 100 patients showed positive patch test reactions to a paste containing 40% sesame oil and a higher proportion showed positive reactions to 100% sesame oil (Malten 1972).
The principal allergens of sesame oil are sesamin and sesamolin (Neering et al. 1975).
In Ngamiland [now a region in Botswana], the leaf of Sesamum schenckii is rubbed on snake bite and is said to have an anodyne action. It produces a blister (Watt & Breyer-Brandwijk 1962).
According to Mabberley (2017), this genus comprises 11 species, all of which occur naturally in Madagascar. Other sources recognise 14 species. They bear large prickly or spiny fruits described as trample burrs, which stick into or around hooves or feet of passing animals as a means of dispersal. The spines vary in size from about 0.75 cm in Uncarina leandrii Humbert to about 5 cm in Uncarina stellulifera Humbert (Midgley & Illing 2009).
The plants have ornamental value and are grown by enthusiasts in succulent plant collections (Shirley 2014).
Referring to Harpagophytum grandidiere [sic], Menninger (1967) noted that the seed pod is a shell-like capsule, 5 inches across, constructed like so many interlaced fish hooks and designed to fasten itself to any creature that touches it. It is dangerous to people and animals alike.