(introduction...)

The sweet potato is a climbing herbaceous plant. It may live for several years, but often it is harvested after 3 months, without waiting for it to flower.

The stems may grow to 2 or 3 metres in length; they are thin and climbing or creeping. They have nodes at varying distances apart. It is thought that the varieties with short inter- nodes yield more heavily than those with long inter- nodes.

The leaves vary greatly in size and shape. Depending on the variety, they may be entire, heart- shaped or deeply divided with three, five or seven lobes. The leaf veins and the leaf- stalks are green or red.

The flowers, usually violet, sometimes white, are clustered in the leaf axils. Many varieties of sweet potato in cultivation do not have time to produce flowers and fruits before the harvest.

The most important part of the plant is the roots, because they can develop into tubers.

The tubers are parts of the creeping roots that have built up food reserves.

These tubers are produced at points where the roots cease to spread out near the surface and turn downward into the soil. By making mounds that are not too wide, the formation of tubers is helped.

Leaves and tubers of sweet potato