わが国の各地をはじめ、朝鮮半島や中国に分布しています。山地の湿った斜面に群生し、茎はみずみずしくて高さは30〜40センチになります。雌雄異株です。葉はゆがんだ長楕円形で、縁に粗い鋸歯があります。4月から9月ごろ、花を咲かせますが、雄花序には短い柄があり、雌花序にはありません。秋には茎の節が膨らんで珠芽(むかご)となり、地面に落ちて増えます。和名は蟒蛇(うわばみ)のいそうなところに生えることから。東北地方では「みず」と呼んで山菜に利用されます。中国語では「楼梯草(lou ti cao)」と呼ばれます。
イラクサ科ウワバミソウ属の多年草で、学名は Elatostema umbellatum var. majus (syn. Elatostema involucratum)。英名はありません。
The "Uwabami-so" (Elatostema umbellatum var. majus) belongs to Urticaceae (the Nettle family). It is a perennial herb that is native to all over Japan, the Korean Peninsula and China. This herb grows in montane wet slopes, and forms a clump, and it can reach 30-40 cm in height. It is dioecious. The leaves are irregular oblong with coarsely-toothed edges. The flowers come in April through September. It flowers from April to September, with short stalks on the male inflorescences and none on the female inflorescences. In the fall, the nodes of the stem swell to form bulbils, which fall to the ground and multiply. Its Japanese name comes from the fact that it grows in places where huge snakes are likely to be found. In the Tohoku region, it is called "mizu" and is used as a wild vegetable. In Chinese, it is called "楼梯草" (lou ti cao).