![]() ![]() Seed production in natural plant populations varies widely from year to year in response to weather variables, insects and diseases, and internal cycles within the plants themselves. However, the seeds do become covered by the cone scales as they develop in some species of conifer. In gymnosperms, no special structure develops to enclose the seeds, which begin their development "naked" on the bracts of cones. Some fruits have layers of both hard and fleshy material. Angiosperm seeds are produced in a hard or fleshy structure called a fruit that encloses the seeds for protection in order to secure healthy growth. ![]() Seeds are produced in several related groups of plants, and their manner of production distinguishes the angiosperms ("enclosed seeds") from the gymnosperms ("naked seeds"). The oldest seed bearing plants were gymnosperms, which had no ovaries to contain the seeds, arising sometime during the late Devonian period (416 million to 358 million years ago) From these early gymnosperms, seed ferns evolved during the Carboniferous period (359 to 299 million years ago) they had ovules that were borne in a cupule, which were groups of enclosing branches likely used to protect the developing seed. The first land plants evolved around 468 million years ago, they reproduced using spores. Nuts are the one-seeded, hard-shelled fruit of some plants with an indehiscent seed, such as an acorn or hazelnut. Different groups of plants have other modifications, the so-called stone fruits (such as the peach) have a hardened fruit layer (the endocarp) fused to and surrounding the actual seed. Sunflower seeds are sometimes sold commercially while still enclosed within the hard wall of the fruit, which must be split open to reach the seed. Many structures commonly referred to as "seeds" are actually dry fruits. In the flowering plants, the ovary ripens into a fruit which contains the seed and serves to disseminate it. In the case of sunflower and corn "seeds", what is sown is the seed enclosed in a shell or husk, whereas the potato is a tuber. "seed" potatoes, "seeds" of corn or sunflower "seeds". The term "seed" also has a general meaning that antedates the above – anything that can be sown, e.g. Seed plants now dominate biological niches on land, from forests to grasslands both in hot and cold climates. Seeds have been an important development in the reproduction and success of vegetable gymnosperm and angiosperm plants, relative to more primitive plants such as ferns, mosses and liverworts, which do not have seeds and use water-dependent means to propagate themselves. The seed coat arises from the integuments of the ovule. The embryo within a seed develops from the zygote, and grows within the mother plant to a certain size before growth is halted. Seeds are the product of the ripened ovule, after the embryo sac is fertilized by sperm from pollen, forming a zygote. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosperm plants. Row 1: poppy, red pepper, strawberry, apple tree, blackberry, rice, carum, Row 2: mustard, eggplant, physalis, grapes, raspberries, red rice, patchouli, Row 3: figs, lycium barbarum, beets, blueberries, golden kiwifruit, rosehip, basil, Row 4: pink pepper, tomato, radish, carrot, matthiola, dill, coriander, Row 5: black pepper, white cabbage, napa cabbage, seabuckthorn, parsley, dandelion, capsella bursa-pastoris, Row 6: cauliflower, radish, kiwifruit, grenadilla, passion fruit, melissa, tagetes erecta.Ī seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. ![]()
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