Seed (Encyclopedia of Science)
A seed is a part of a flowering plant involved in reproduction. It consists of three major parts: the embryo, endosperm, and testa. The embryo is produced when male and female elements are combined during reproduction. It will eventually grow into a new plant. The endosperm is a collection of stored food the young plant will use as it begins to germinate, or grow. The testa is a tough outer layer that protects the embryo and endosperm from damage by outside factors.
Two kinds of seed plants exist. Gymnosperms are plants that produce naked seeds. The most common type of gymnosperms are conifers, cone-bearing trees and shrubs such as firs, hemlocks, junipers, larches, pines, and spruce. Angiosperms are plants whose seeds are enclosed in a protective structure called the fruit. Angiosperms are also known as flowering plants because they produce flowers in which seeds are produced and in which they develop.
Seeds are produced when pollen is released from the male (stamen) part of a plant. That pollen comes into contact with the ovules of the female (pistil) parts of a plant. Some kinds of plants contain both male and female organs on the same plant. In that case, self-fertilization can occur when pollen from one part of the plant fertilizes ovules on another part of the same plant.
In most plants,...
(The entire section is 1406 words.)
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