Angiospermae make the most numerous group of the higher plants, it includes about 250 thousand types which can be found on all globe. Distinguish two ways of reproduction of angiospermous plants — sexual and sexless.
Instruction
1. A flower call the modified shortened escape intended for reproduction of angiospermous plants. Some flowers have stamens and pestles, they oboyepoly, for example, at an apple-tree, a tulip, potatoes, pear. Others possess only stamens, call them men's or tychinochny. If flowers have only pestles, they are carried to women's or to pistillate plants. Diclinous flowers are characteristic of corn, a willow, a poplar, a cucumber and many others.
2. The main sign of Angiospermae — existence of the flower playing an important role in reproduction. Unlike gymnospermous, at Angiospermae of a semyazachatka are protected, they are in a pestle ovary cavity. Pollen gets at first not in pyltsevkhod a semyazachatka, and on a snout of a pestle which is intended for her catching.
3. Double fertilization after which the zygote which gives rise to a germ is formed and also a trishyuidny cage is characteristic of Angiospermae, of it it is formed endosperms subsequently. Are simplified by gametogophytes at Angiospermae and develop much quicker, than at gymnospermous. Simultaneous development of a germ and endosperm of Angiospermae allows to avoid waste of energy and nutrients if the germ is not formed.
4. Process of fertilization is preceded by pollination, distinguish two of its types — self-pollination and cross-pollination. In the first case pollen grains get on a snout of a pestle of the same flower, in the second — pollen is transferred from stamens of one plant to a snout of a pestle of another.
5. Only one individual who is capable to form disputes participates in asexual reproduction or to separate viable sites of a vegetative body of which affiliated individuals are formed. A set of angiospermous plants form special vegetative rudiments — lukovichka, vyvodkovy kidneys, klubenk. This way of asexual reproduction at plants is called vegetative.
6. At most of groups of plants the vegetative reproduction prevails over sexual. There are types which breed only vegetativno. One of the main features of asexual reproduction is an opportunity to keep all qualities of a parental form, it is actively used by the person to keep genetically clean lines in gardening and selection.
7. Under natural conditions plants, as a rule, breed through the same bodies, however in agriculture the set of ways of artificial vegetative reproduction is developed. It is applied if seeds are not formed or at seed reproduction it is impossible to keep genetic purity of a grade.