Seed Structure and DevelopmentFollowing the fertilizations in the embryo sac, the zygote divides repeatedly by mitosis and differentiates into an embryo. The endosperm nucleus also divides by mitosis and forms the endosperm tissue, which provides food for the developing embryo. The early embryo is linear with apical meristems on either end and one or two seed leaves or cotyledons. The axis below the cotyledons is called the hypocotyl, at the tip of which is the radicle that gives rise to the primary root of the seedling. The axis above the attachment of the cotyledons is the epicotyl, which also ends in an apical meristem. In some seeds, the first foliage leaves are formed in the seed. The area above the cotyledons is thus a miniature shoot and is called the plumule. In some taxa, food for the embryo remains within endosperm tissue and the cotyledons
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