A seed forms when the fertilized egg divides by mitosis. It stores food and has the potential to become a new plant under optimal conditions. Fertilization is the process of merging the male gamete and the female gamete to form a zygote. About 80 to 85 percent of our caloric needs are met through seeds, either directly as food or indirectly through use as food.
Seeds are the result of plant reproduction. During the flowering period, male and female tissues interact with each other in a variety of ways. When pollen falls on the stigma of the flower, it germinates and forms a pollen tube, which then grows rapidly towards the plant's ovary. Once it finds an egg, the pollen tube bursts to release sperm, which fertilize the egg and start seed formation.
The flowers of a plant are designed for the purpose of producing seeds. If a flower is pollinated, fertilization can occur and a seed develops in the ovary of the plant. This is sexual reproduction and ensures genetic diversity. As the fertilized seed develops, so does the fruit (seed, pod, or capsule, etc.).
The seeds are the product of the mature egg, after the embryonic sac is fertilized by pollen sperm, forming a zygote. The embryo within a seed develops from the zygote and grows inside the parent plant to a certain size before growth stops. The seed coat arises from the egg integuments. Therefore, this innate true or latent latency is caused by conditions within the seed that prevent germination.
The oldest seed-producing plants were gymnosperms, which had no ovaries to contain the seeds, emerging sometime during the Late Devonian period (416 million to 358 million years ago). Of these early gymnosperms, seed ferns evolved during the carboniferous period (359 to 299 million years ago); they had eggs born in a dome, which were groups of enveloping branches that were probably used to protect the developing seed. Plants that produce smaller seeds can generate many more seeds per flower, while plants with larger seeds invest more resources in those seeds and usually produce fewer seeds. As a result, plants have evolved in many ways to disperse their offspring by dispersing their seeds (see also vegetative reproduction).
Taxonomists have described the first true seeds of the Upper Devonian, which probably became the theater of its first true evolutionary radiation. Seed viability is the embryo's ability to germinate and is affected by a number of different conditions. Inside the seed, there is usually a supply of nutrients for the seedling that will grow from the embryo. Seeds have been an important development in the reproduction and success of gymnosperm and angiosperm plant plants, compared to more primitive plants, such as ferns, mosses and liverworts, which are seedless and use water-dependent media to propagate.
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. In endosperm seeds, there are two distinct regions within the seed cover, an upper and larger endosperm and a smaller lower embryo. Many garden plant seeds germinate easily as soon as they have water and are warm enough; although their wild ancestors may have been asleep, these cultivated plants lack it. In summary, very little is known about the molecular mechanisms that activate both female gametes that lead to the onset of seed development.
Although the cdka; 1 mutant core cell showed mitotic divisions after egg fertilization, it appeared mostly unfertilized, and endosperm proliferation and therefore seed development stopped after a certain time point. The nature of this material is used both in the description and classification of seeds, in addition to the relationship between embryo size and endosperm. Seeds are produced in several related plant groups, and their form of production distinguishes angiosperms (closed seeds) from gymnosperms (bare seeds). In gymnosperms, no special structure is developed to enclose the seeds, which begin their development naked on the bracts of the cones.