The long stem in the middle of leek is called leek moss. There are two kinds of leek stems, one is a flower stem that grows on the ground, and the other is a vegetative stem that grows underground. The flower stem is in the reproductive growth stage of leek, and the terminal bud of stem disc develops into flower bud, which produces flower bud (also called leek bud). The stem is about 50 cm high, and there is an involucre at the top of the flower bud, in which there are flower organs. Flowering stems are channels for leek plants to transport nutrients to promote the development of flowers and fruits. The oblate embryo form of vegetative stem is a flat disc-shaped stem with leaf sheath at the top and rooting system around it, which is called "stem disc". Its terminal bud is surrounded by the lower part of leaf sheath, so it won't freeze to death in winter. Leaves grow in the upper part of the stem disk, and fibrous roots grow in the lower part. With the growth of plant age and tillering year by year, the vegetative stems continue to extend to the ground to form branches, so they are also called "rhizomes". The vegetative stem is the meristem of new roots, leaves and tillers of Chinese chives, and it is also an important organ for storing nutrients in winter.