Komatsuna or Japanese mustard spinach is a leaf vegetable. It is a variety of Brassica rapa, the plant species that yields the turnip, mizuna, napa cabbage, and rapini. It is grown commercially in Japan and Taiwan. The name komatsuna is from the Japanese komatsuna, "small pine tree greens". It is stir-fried, pickled, boiled, and added to soups or used fresh in salads. It is an excellent source of calcium. 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 centimeters 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. The plant is also used for fodder in some Asian countries.