November 30, 2021

The seed is a reproductive plant organ present only in bare seeds and hidden seeds by which the plant survives adverse environmental conditions and in which the germ, the beginning of a new plant, is located. It develops from a seed embryo, after fertilization. It differs: seedlings and nucleus.The nucleus contains the germ (embryo) and endosperm, or just the germ. The germ originates from a diploid zygote, a haploid egg connected to a haploid spermatic pollen cell. The endosperm has a triploid number of chromosomes because it is formed by the fusion of a secondary, central cell of the embryo sac that is diploid with another (haploid) sperm pollen cell. In gymnosperms, the endosperm is haploid and is formed before fertilization, so it is also called primary. It usually shows an umbilical scar (hilum) (white dot in wild chestnut seeds) and a micropile opening through which the seeds absorb moisture and through which the root grows during germination. The seed can have other additions (arilus, curinkulus, cryoca ...) The size, weight and shape of the seeds vary greatly in different types of plants. Especially large seeds have some palms such as Double Coconut Lodoicea maldivica (JF Gmelin) Persoon up to 20 kg, and the smallest are in orchids (hundredths of a milligram). An interesting example is carob (Ceratonia siliqua L.) whose seeds have such a constant (unchanging) weight of 0.2 g, that they served as weights for measuring precious stones and pearls, so (carat) was named after carob. Each plant produces a large number of fruits and seeds (or only seeds in gymnosperms) with which it spreads and thus ensures the survival of its own species. Not every grain develops into a new plant. Many seeds end up in unfavorable conditions for germination and development. The creation of a large number of seeds, in fact, ensures that as many of them as possible are found in favorable conditions and develop into a new plant. Seed types According to the type of nutrient tissue and the place where it is located, it differs: seeds with endosperm (albumin), in which the endosperm forms the main mass, while the germ is an insignificant part of the seed; the most common is the type of seed; it is found in cereals and all other grasses, plants from the Solanaceae family, lilies (Liliaceae) all �

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