Japanese name: ミヤマタニソバ（深山谷蕎麦） Scientific name:Persicaria debilis
[Overview]
An annual 10–30 cm tall, found in forests in the mountains.
The stem is erect or ascending, and usually has downward-pointing bristles only at the nodes.
The leaves are simple and alternate, triangular, 1.5–6 cm in both length and width, and entire.
The leaves are thin and have fine hairs on both sides; the upper surface usually has a dark purple inverted-V mark.
The ocrea is short, and at least on the leaves at the top of the stem its tip is leaf-like.
The petiole is slender.
Slender branches emerge from the stem tips and leaf axils, each bearing 2–5 flowers at the tip.
The flowers have no corolla; the white calyx is conspicuous.
The fruit is a glossy, three-angled achene.
