アブラナ科アブラナ属の一年草で、学名は Brassica rapa var. chinensis。英名は Pak choi。
The Pak choi (Brassica rapa var. chinensis) belongs to Brassiaceae (the Mustard family). It is an annual herb that is native to the reach of Chang Jiang River of China. Other cultivars of chinese group were introduced into Japan in early days of Meiji period (1868-1912), and were breeded many local varieties such as "Seppaku tai-sai", "Nagaoka-na". Pac choi was introduced into Japan in the first half of 1970s. It is 25 cm tall, does not form a head, and has thick, greenish petioles that overlap tightly, with the tips of the leaves open. The name is made it a rule to call that "Chingen-sai" with light green leafstalk and "Pac choi" with white one.