Cotyledons are temporary leaflike organs, and their number is quite stable in angiosperms. Mature embryos with only one cotyledon are called monocotyledonous plants, such as wheat and lily. Dicotyledonous plants with two cotyledons, such as rape and soybean, are called dicotyledonous plants.

The number of cotyledons in embryos varies with plant species. Monocotyledons have 1 cotyledons, such as maize and lily. Dicotyledonous plants have two cotyledons, such as soybeans and pears; The number of cotyledons of gymnosperms varies greatly, such as 2 cypress trees, 3 ginkgo trees and many pine trees.

Extended data

Cotyledon is one of the components of seed plant embryo, and it is an organ for storing nutrients or assimilating during seedling stage. In endosperm-free seeds (dicotyledons), cotyledons are particularly thick and store a lot of nutrients.

In the seeds with endosperm (monocotyledons), cotyledons are underdeveloped, but they can absorb nutrients from endosperm and transport nutrients for embryo development, so cotyledons play a very important role in the early stage of seed germination and seedling formation.

When seeds germinate, they must first absorb water. Nutrients in cotyledons or endosperm are transported to radicle, embryo and hypocotyl. Subsequently, the radicle develops, first breaking through the seed coat and forming roots. The hypocotyl is elongated and the embryo develops into stems and leaves.

Baidu encyclopedia-cotyledon