Japanese name: ナガイモ（つくねいも群）（長芋） Scientific name:Dioscorea polystachya
[Overview]
A dioecious climbing perennial. Most plants are female.
Taxonomically, the Icho-imo group is the same species, and the two are distinguished by the shape of the tuber and similar features.
The stem has ridges and, like the leaf stalk, is tinged with purple.
The leaves are usually opposite and heart-shaped to ovate. Bulbils are hardly ever borne in the leaf axils.
This Naga-imo, also called the Yamato-imo group, has a lump-shaped tuber (rhizophore) like a clenched fist.
[Uses]
Among the Yama-imo types, it is the stickiest and has the best flesh, so there is demand for it as a high-grade food ingredient.
[Cultivation]
Propagate from seed tubers.
Because it grows deep into the soil, the ground must be cultivated to a depth of nearly 1 m.
