Late Mesozoic and the Cretaceous period of the planet's biomass is characterized by domination and wide distribution of a new branch of the evolution of algae - angiosperms, or flowering plants.The reasons for this phenomenon were the special tools available in the arsenal of the structure of the group.
Today, flowers, seeds and fruits they produce are not only an important link in the food chain most biogeocenosis, but also a source of food for people, drug raw materials, economic materials and so on.There are more than 250 thousand of angiosperms, which exist in a variety of life forms (trees, vines, grasses, shrubs) and inhabit almost all parts of the world, continents and the continents.
classification of angiosperms
Authority seed reproduction in flowering plants - the flower itself.That is its structure, appearance, and a number of other morphological characters of angiosperms entire department is divided into two main classes:
- Monocots.There are about 63 thousand species, united in 122 families.Also, a class consists of 3 thousand births.The most common family: Cereals, Liliaceae, ovoid, Palm, Orchids, Sedge, bromeliads, Nymphaeaceae, pepper and others.
- bipartite.More than 190 thousand species, united in 10,000 genera and 418 families.The most common of the latter: Cruciferous, Rosaceae, Myrtaceae, Grape, butterfly or beans, Solanaceae, Umbrella and others.
The main differences between these classes are in the structure of flowers, root, leaf.The economic importance of these plants is very large (vegetable and fruit crops, receiving textiles, construction materials, dyes, medicines, etc.), as well as a role in nature.
evolutionary innovations in the structure
are such we can highlight a few.These are the attributes that have allowed angiosperms settle so widely in the world, be so hardy and adapted to the habitat and climatic conditions of the environment.
- Authority seed reproduction in flowering plants - flowers and formed after the fetus.The seed is protected, covered with fruit pulp or hard skin, which gives a great advantage to the survival of species and their resettlement.
- A variety of methods of vegetative propagation.
- Numerous types of pollination.
- Devices internal structure to complex environmental conditions (drought, excessive moisture, bright sun or a lack of, frost, etc.).This enhanced conduction system, flowers, seeds, fruits, powerful roots and so on.
- diversity of life forms.
- reproduction of flowering is independent of the presence of water.
All these features have allowed these plants to occupy the land everywhere and become leaders among the flora.
reproductive organs of flowering
Authority seed reproduction in flowering plants - a flower, a fruit and then covering the developing seed.Features of the structure of the flower, its unique structural parts, methods of pollination and development - all this makes the angiosperms unique champions among the plants on the reproductive function.
For a man flower - is an aesthetic perfection, which can be admired, to give and please others, inhale a pleasant aroma.However, the value in the nature of the structure is quite obvious - an organ of seed reproduction in flowering plants.The functional significance is determined by the processes of fertilization and development of the sporophytes of seed.
structure of the flower
Flower and fruit of any member of the angiosperms in structure ingeniously conceived and organic.The combination of all the parts of the plant allows to perform reproductive functions in full, regardless of the climate and other abiotic environmental factors.
consider the general features of the structure of the flower.
1. Stem part:
- peduncle;
- receptacle.
2. Sheet component.Founded sepals (usually green), and petals forming the corolla.Its color can be very different, from white to dark purple.
3. generative parts.Reproductive organs, to ensure reproduction of flowering plants.It pistils, stamens, the ovary.
Outside the main generative components demarcated and protected perianth.This structure includes:
- cup of sepals;
- colored corolla of petals.
perianth may be single or double, depending on the type of plant.It contains a large number of different substances: essential oils, pigments (carotenoids, xanthophylls, chlorophyll, anthocyanins, and other antofeinov).Precisely because of this flower exudes the aroma that attracts pollinators.Corolla has a different size and coloring, it is also important to lure insects, birds, animals.
Directly body breeding flowering plant consists of gynoecium and androecium, under cover of the perianth.Androecium - a collection of all the stamens, performing the function of the male reproductive organ.Stamens simple structure, represented by such structures:
- staminal filament;
- boot of two halves connected by a courier;
- microsporangia - nest within the anther, in which the process microsporogenesis and microgametogenesis (formation of sperm cells and microspores).
Through the binding thread Staminate anther peduncle, the exchange of nutrients and metabolic products.The resulting microspores subsequently formed male sporophyte.Sperm lead to the formation of dust who will participate in fertilization and seed formation.
flower gynoecium formed by the totality of all of its constituent pistils.This structure is important, as it represents, as already mentioned, the female reproductive organ.The pistil consists of:
- ovary;
- column;
- stigmas.
Ovary - structure that forms the widest part of the pistil.Inside formed ovules involved in the formation of the pericarp.Inside these structures and processes occur megasporogenesis megagametogeneza.Also in the ovary is the process of fertilization and seed formation, its development.
Column pestle can be different sizes.It serves for communication between stigma and ovary.Different sterility, that is not taking part in the sexual process.
stigma serves to trapping dust particles, which fall from the stamen anther.The size and shape of these parts is different, depending on the type of plant pollination.
Flowering plants: reproduction
flower may contain a different number of stamens and pistils.There are some species in which there are only stamens or pistils only - they are called male and female respectively.
The more interesting flowering plants?Propagation they can be both sexually and asexually, t. E. Vegetative.About sex it is, if involved the reproductive parts.This process is called double fertilization.
Its essence is as follows.After pollination, the plants fertile (active) pollen lands on the stigma and held there through a viscous medium and special sticky components.Then mired cell begins to grow inside them, forming a pollen tube.It is for her to get two ovaries sperm with haploid set of chromosomes.Once inside the ovule, one merges with the egg, fully developed and ready for this process.So there is a zygote - diploid and later giving rise to seed.
second sperm fuses with the ovule in diploid cells at the center.The result is the endosperm.The following processes complete the reproductive function:
- ovule integuments of seed coat is formed;
- base wall pestle to form the pericarp;
- ovule produces all the seed as a whole.
The result is the development of seeds inside the fruit.
methods of pollination
There are several basic options by which pollen falls on the stigma.Thus, we consider ways of pollination of angiosperms:
- Selfing - without the participation of foreign individuals.
- by wind.
- Thanks insects, animals, birds.
- with water.
- artificial pollination - with the help of people.
Vegetative reproduction
reproduction of colors is also carried out vegetatively, that is, without the sexual processes.These methods are very diverse.The point is to use various parts of the shoot (root, leaf, stem).Some of the most common options:
- layering;
- mustache;
- vaccination;
- roots;
- leaf and stem.
Most of these methods is used by people at a dilution of vegetable and fruit crops.
seeds of angiosperms
Different plants - different seeds.The structure of this structure is similar, but the form, structure, color may vary.In addition, plants may be annual and perennial.Annuals reproduce only by seeds, which ripen, usually in late summer.Thus, the new generation will only appear in the next growing season.Seeds of annual flowers are often used by people for different kinds of ornamental plants.The latter include asters, eschscholzia, marigolds, begonias, datura, calendula, wallflowers, Cosmo, miralibis and many others.
Fruits flowering
flower and fruit - the most important part of the angiosperms.They allow these plants exist in different environments, be widely adapted and numerous.
fruits of plants distinguished by great diversity of species, their examination, classification and value botanists studied all over the world, the science of them is called karpologija.The most common are berries, drupes, apples, melon, granatina, pod bean weevil, leaflets, lionfish, Hesperides and others.
