Analysis: Sexual germ cells produced by parents become fertilized eggs through the combination of bisexual germ cells (such as sperm and egg cells), and then the fertilized eggs develop into a new individual reproductive mode, which is called sexual reproduction; Asexual reproduction refers to the reproductive mode in which new individuals are directly produced by the mother without the combination of bisexual reproductive cells.

A. Sexual reproduction is a reproductive mode in which germ cells combine to form a fertilized egg, and then the fertilized egg develops into a new individual, such as plants propagating through seeds.

B, asexual reproduction is a way to produce new individuals directly from the mother, without germ cells. In essence, somatic reproduction is asexual reproduction. The main types include fission propagation, spore propagation, budding propagation and vegetative propagation (grafting, layering, cutting, etc.). ), tissue culture and cloning. In the process of growing many small plants on the leaf edge of "rooting", there is no combination of hermaphroditic germ cells, which is consistent with.

C. spore reproduction depends on spore production. Spores can germinate and grow new individuals under appropriate conditions, such as temperature and humidity. This reproduction method is called spore reproduction, such as spore reproduction of algae, moss, ferns and fungi. It doesn't fit the question.

D. Grafting refers to grafting the buds or branches of one plant to another plant, so that the combined two parts grow into a complete plant. It belongs to vegetative reproduction and does not meet the meaning of the question.

So choose: B.