Japanese name: オオイタドリ（大虎杖、大痛取） Scientific name:Fallopia sachalinensis
[Overview]
A perennial 1–3.5 m tall, found in mountains and fields.
A thick rhizome develops, and it often forms colonies.
The stems branch in the upper part, curve in an arch, and are often tinged with red.
Leaves are simple and alternate, long ovate to ovate, 15–40 cm long and 10–25 cm wide, with a pointed tip and a cordate base.
The underside of the leaves is tinged with a powdery white.
The leaf margins are entire.
There is a leaf stalk.
It is dioecious.
Both male and female plants produce racemes gathered in panicles at the stem tips and in the leaf axils, bearing many densely set flowers.
The male inflorescences stand upright, while the female inflorescences hang down.
The flowers have no petals; the milky-white calyx, divided into 5 lobes, is conspicuous.
In the male flowers, 8 stamens extend long.
The fruit is an achene with 3 ridges and 3 wings.
[Uses]
The young stems are used as a wild vegetable.
The rhizomes are used medicinally.
