The "Sankaku-i" (Scirpus triqueter) belongs to Cyperaceae (the Sedge family). It is a perennial herb that is distributed throughout Japan and Eurasian Continent. This herb grows in marshes or along streams and can reach 50-100 cm in height. It spreads by rootstocks and borns triquetrous stems. The leaves are degenerate, turn to sheaths and wrap the underpart of stems. The petiolated clusters are borne on the stem apices from July to October. The inflorescences are topped by bract leaves. It is similar to "kangare-i", but has a stalk on the inflorescence. In Taiwanese Chinese, it is called "蒲" and in Chinese "三棱水葱" (san leng shui cong).