  
 
Dioscorea is a large genus of flowering plants in the family Dioscoreaceae, native throughout the tropical and warm temperate regions of the world. The vast majority of the species are tropical, with only a few species extending into temperate climates. It is named after the ancient Greek physician and botanist Pedanios Dioscorides. Mostly they are tuberous herbaceous perennial climbers, growing 2 to 12m in height. The leaves are spirally arranged, mostly broad heart-shaped. The flowers are individually inconspicuous, greenish-yellow, with six petals; they are mostly dioecious, with separate male and female plants, though a few species are monoecious, with male and female flowers on the same plant. The fruit is a capsule in most species, a soft berry in a few species.   
  Several species, known as yams, are important agricultural crops in tropical regions, grown for their large tubers. Many of these are toxic when fresh, but can be detoxified and eaten, and are particularly important in parts of Africa, Asia, and Oceania. Caudiciform species include Dioscorea elephantipes, Dioscorea dregeana, Dioscorea hemicrypta, Dioscorea macrostachya, Dioscorea mexicana, Dioscorea rupicola, Dioscorea sansibarensis and Dioscorea sylvatica. One class of toxins found in many species, including Dioscorea sylvatica, is steroidal saponins, which can be converted through a series of chemical reactions into steroid hormones for use in medicine and as contraceptives. They do very well in pots and rockeries.
Dioscorea rupicola is found in South Africa, Mozambique, Zambia and Tanzania, growing in rich and well-drained soil. This winter growing caudiciform was given its name by Carl Sigismund Kunth in 1950. The caudex can grow to 80 centimeters in diameter and can reach three meters in height. The vines will reach eight meters in height. The flowers are brownish green. It forms a large above ground tuber, sometimes called a caudex, which can be raised for effect as an unusual succulent bonsai. Keep it dry in summer which is its dormant period. 
   
  
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