Komatsuna (Brassica rapa var. perviridis or komatsuna) is a type of leaf vegetable. It is a variant of the same species as the common turnip. It is grown commercially in Japan, Taiwan and Korea; the name is from Japanese komatsuna. It is also known as Japanese Mustard Spinach and is usually stir-fried, pickled, boiled and added to soups or used fresh in salads. It is an excellent source of calcium. It is also used for fodder in some Asian countries. The leaves of komatsuna may be eaten at any stage of their growth. In a mature plant they are dark green with slender light green stalks, around 30 cm long and 18 cm wide. It is most often grown in the spring and autumn, as it cannot endure extreme heat or cold for more than a short time.