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Thursday, July 3, 2014

Wild Cucumber (Cucumis africanus)

 Family Cucurbitaceae
Description
Perennial herb. Rootstock thick and woody. Stems annual, up to more than 2 m long, finely ridged, roughly whitish hairy, usually prostrate, but will climb on bushes and other support; cut twigs exude clear sap. Leaves broadly ovate, deeply 5-palmately lobed, 15-115 mm long, dull green, roughly hairy on both sides with bulbous-based hairs; crushed leaves non-aromatic. Leaf stalks finely ridged and roughly hairy, up to 80 mm long. Tendrils simple. Flowers pale to dark yellow with green veins, either male or female, both appearing on the same plant (monoecious). Male flowers in groups of 5-10, petals up to 9 mm long. Female flowers solitary, petals up to ± 11 mm long. Ripe fruit 30-80 x up to 3o mm, prickly, prickles up to 10 mm long, fleshy to hard, base flat; unripe fruit longitudinally striped dark and light green, maturing to greenish yellow or white, striped purplish brown or yellow, prickles mainly on dark bands; occurring in two distinct forms, either small, ellipsoidal, bitter and poisonous when ripe, or large, cylindrical, non-bitter and edible when ripe; flesh green and translucent, many-seeded. Seeds elliptic, about 4.5 x 2.5 mm, and 1 mm thick, cream-coloured.

Distribution
C. africanus is indigenous to Africa and occurs from the woodlands of Angola and Zimbabwe to Namibia, Botswana and South Africa. In South Africa it is found in Limpopo, North-West, Gauteng, Mpumalanga, KwaZulu-Natal, Northern, Western and Eastern Cape. It is rare in Mpumalanga, KwaZulu-Natal and the Eastern Cape.


With its wide distribution, C. africanus grows in a large variety of vegetation types. Collectors have recorded the following: Karoo and Karroid types such as Namaqualand Broken Veld, Karroid Merxmuellera Mountain Veld, also with Schmidtia kalahariensis, Salsola and species of drought-deciduous scrub as well as Renosterveld, grassland and False Grassland. Also listed are savanna and various kinds of woodland e.g. Kalahari Thornveld with Colophospermum mopane, Combretum, Terminalia and many species of Acacia. It is quite rare in the swampy coastal grassland of KwaZulu-Natal.
Ecology
C. africanus flowers and fruits from about September to May, but mostly in March. Some 120 fruit per plant have been observed. In southern Africa it grows from 150 to 2 115 m altitude in areas of very low to moderately high rainfall, from under 100 800 mm annually; one record from the KwaZulu-Natal coast is exceptional. It can withstand high soil temperatures (one collector measured 47.5°C at about noon), but thrives in partial shade where the leaves will be larger and somewhat less hairy. On a very hot day, the leaves have been observed to stand at a 90° angle to the soil surface. At least the underground parts are frost hardy. Bees visit the flowers, presumably other insects too.


Uses and cultural aspects
In South African traditional medicine the fruit, leaf or root of C. africanus is used as an emetic, purgative or enema for various ailments. The boiled leaf is used as a poultice. The plant has also been used as an animal medicine. The poisonous form of the fruit contains the bitter principle cucumin ; incidents of human and cattle poisoning have been recorded (Watt & Breyer-Brandwijk 1962). According to Meeuse (1962), there are three types of fruit with increasing amounts of the bitter substance.

The fresh young leaves are eaten as a pot herb by many rural people. Arnold et al. (1985) found that the leaves are rich in calcium, iron, nicotinic acid and vitamin C. The fruits have an overall nutrient composition slightly better than that of the cucumber and is sought after as a water source by the Khoisan of the Kalahari and in other dry areas. R.Marloth, the famous South African botanist, noted on his specimen no. 10040 (now in the National Herbarium), that he bought agurkies in a shop in Cape Town in January 1921. He found the flavour slightly acid and the odour of the pulp like real cucumbers.

The non-bitter fruits of C. africanus have been pickled and preserved at the Cape since the late 17th century. Recipes for these delicacies are found in several publications e.g. Rood (1994). The same recipes can be used for the cultivated West Indian gherkin, C. anguria var. anguria. This plant was taken by slaves from West Africa to the West Indies where it was domesticated.