When a plant reaches its maximum and a certain size and passed a series of developmental stages, it starts propagation ( reproduction ). Asexual repr

Plant propagation methods [reproduction]

When a plant reaches its maximum and a certain size and passed a series of developmental stages, it starts propagation (reproduction).

Asexual reproduction

In unicellular forms occurs separation of it in two individual cells, which grow and divide again. More difficultly organized plants can propagate by division of the body into sections, each of which becomes an independent plant. Many flowering plants (e.g. water plant Elodea canadensis), dissected into parts, recover from each of them a new plant. This method of reproduction is called vegetative propagation.

With the development of the vegetable world the ability to form new elements concentrated in certain areas of the body. Thus such features have, for example, apical cells that continue the growth of the individual in a specific direction. Similarly, the ability to form new individuals remain mostly only a certain parts of the plant body, on which the special reproductive organs are formed.

In the reproductive organs form single cells, which are able to restore the entire organism, when are separated from the mother plant under favorable conditions. This method of propagation, when in special organs form the cells, that reproduce the whole individual in further development and that are essentially also a part of the parent plant, is called propagation by spores (sporogenesis). Organs that serve for such reproduction are called sporangia, and the elements (cells), that form in them — disputes.

These two methods of asexual reproduction can be contrasted with sexual reproduction.

Sexual reproduction

Sexual reproduction is fundamentally different from asexual. In this case, there is a sexual process (fertilization) — fusion of two cells, called gametes (germ cells or sex cells) — paternal and maternal, at that plasma and nuclei of these cells fuse. Gametes arise in certain cells or organs of plant.

Organisms that produce gametes, because of its growth in a little (and sometimes very sharply) different conditions, have a little different hereditary properties that have arisen as an adaptation to living conditions.

A new cell, called a zygote that forms as a result of two gametes fusion, develops into a new organism, radically different from the organisms that have produced the gametes, as it contains the hereditary properties of the paternal and maternal organisms.

This dual inheritance of zygote provides much greater viability of developing body, which as result has a greater adaptability to the changing conditions of life.

Germ cell of the body completes a cycle of development, and is biologically the most complex in the body. The hereditary characteristics of an organism are expressed in most in the germ cell. It is clear that as a result of the fusion of two gametes from different individuals, the zygote develops into much more viable organism in comparison with the organism that occurred as a result of self-fertilization.

What is the relationship of gametes at fertilization? Each process in the body is a physiological process, the metabolism, based on assimilation and dissimilation. Undoubtedly, these processes also occur at the fusion of two gametes. Zygote — is not a mechanical fusion of two gametes, but a new — the third cell, that has formed from the mutual assimilation of gametes. Taken from http://worldofschool.org

During the fertilization merge not only the cores of gametes, as it was considered for a long time, but also their protoplasts, i. e. the nucleus and cytoplasm. Even the most highly organized plants — angiosperms — female gamete (ovum) and male gamete (sperm) are cells.

During the fertilization, in fact, occurs not the reproduction of current organism, but the origination of a new; that’s why sexual reproduction is often called procreation. If no gamete fusion occurs — they die.

Taking into account the vital functions of plant organisms, their body is divided into vegetative organs, supplying primarily the needs of current individual, and the generative organs, ensuring the existence of a systematic unit to which this individual belongs, — the organs of sexual reproduction. In flowering plants vegetative organs are root, leaf and stem. Generative organ is a flower.