The chamber bitter (Phyllanthus urinaria) belongs to Euphorbiaceae (the Spurge family). It is an annual herb that is distributed from south of Honshu in Japan to China, Southeast Asia, India and Sri Lanka. This herb grows generally on the roadside and in the field, and up to a height of about 10-30 cm. The stem is reddish. The leaves are elliptic and alternate with the twigs extending sideways. It produces male flowers at the tip of twigs and female flowers on the inner leaf axils from Luly to October. The Japanese name is derived from comparing a red brown spherical fruit to "Mandarin". When leaves hit the rain, they have a habit of closing inside.