They are seen as a sweet soothing herb that stimulates the stomach and spleen and has a tonic effect on the lungs and kidneys. The tuber contains allantoin, a cell-proliferant that speeds the healing process. It is used internally in the treatment of poor appetite, chronic diarrhoea, asthma, dry coughs, frequent or uncontrollable urination, diabetes and emotional instability. It is applied externally to ulcers, boils and abscesses. The tubers are harvested in the autumn and can be used raw or baked.
Propagation is a simple matter.
Do not remove this top portion until you want to eat the yam, though, because it will store much better in one piece. Yams also form tubercles in late summer and early autumn. These are pea-size swellings in the leaf axils and they fall off the plant when they are ripe. These tubercles are actually baby tubers and are an excellent way of propagating a quantity of the plants. Try and harvest them just before they are ready to fall from the plant and store them in a cool, frost-free place over the winter.