マメ科クサネム属の一年草で、学名は Aeschynomene indica。英名は Indian jointvetch。
The Indian jointvetch (Aeschynomene indica) belongs to Fabeceae (the Pea family). It is an annual herb that is native throughout Japan, as well as in the temperate to tropical areas of Eurasian Continent, Africa and Australia. This herb grows in wet rice fields or stream banks, and can reach 50-100 cm in height. The leaves are pari-pinnate compound with 20-30 linear-oblong leaflets. The flowering stalks are borne on the axils, and the pale yellow papilionacenous flowers bloom from July to October. The leaflets close at night. In Taiwanese Chinese, it is called "合萌" and in Chinese "合萌" (he meng).
In Korean, it's called "ja-gwi-pul" (자귀풀). This is a compound word consisting of "mimosa" (ja-gwi: 자귀) + "grass" (pul: 풀). The name comes from the fact that the leaves resemble those of the mimosa (ja-gwi-na-mu: 자귀나무), and the plant exhibits a "sleep movement" at night, with the leaves facing each other and overlapping.