Group angiosperms formed over 125 million. Years ago.And until now, there are disputes about the specific period (era) of their occurrence.Some call the Cretaceous period, others speak of an earlier stage, the third claim in later.
one thing remains indisputable: this category of plants occupied a dominant position and sat perfectly on all pieces of the globe, ranging from tropical rain forests and ending with hot and icy deserts of Africa and the Arctic.
What they angiosperms?Examples, characteristics and properties of the taxon, the classification will consider below.
angiosperms: general characteristics
The name of this group received for its ability to harbor the seeds of soft or hard tissues of the fetus.After all, in place of the flower, which is the hallmark of a taxon, formed a variety of shapes and sizes, color and nutritional value of the structure.They are called fruits.
plant itself - is an escape, leaving the root system in the ground and having a flower, stem and leaves.Reproductive organs, characterizing the structure and allows to adapt to any habitat and conquer new territories for settlement - this is the flower.
more progressive structure, which appeared during the evolution of the features and tools allow to oust representatives of gymnosperms, mosses and fern.Today, in the flora of our planet is dominated by a beautiful, vibrant, diverse in life forms angiosperms.Examples of these can result in a very long time, because birth alone there are more than 13 thousand.Briefly we can say this: all the plants with flower - it angiosperms.
general plan structure
main bodies that have a representative of the group - those that are common to all higher plants: root, stem, leaf.Additional structures that ensured angiosperms opportunity not depend on the water for the breeding process, became a flower.
of the flower: stipules, receptacle, peduncle, corolla of petals, bud, pistil, stigma, stamens.All of these structures are important as the reproductive organs, as well as those who later transformed into a fetus, which protects the seed to full maturity.
People appreciate the flowers of plants for extraordinary beauty and tenderness, pleasant aroma.Use of the healing properties of extracting useful extracts are grown to produce in the future, juicy and tasty fruit.
for flower plants themselves - a useful an important body, which delivered them out of the water, depending on the breeding, because now it is done with the help of double fertilization.Fruits provide security and protect the seeds, as well as participate in their dispersal by eating animals, it is also a big plus, releasing the structure of angiosperm plants among others.
different structure of flowers, the variety of their forms allows to increase methods of pollination, which also contributes to the wide dissemination and resettlement of plants.
Distinguishing features
Of course, the most important and reliable innovation for flowering was the formation of the flower.But not only this, but other signs of angiosperms favorably emphasize and confirm their dominance of the mass among the flora.Such as for example:
- presence of more advanced conduction system, including sieve elements of the phloem and phloem tissue.This allows you to more quickly transport the necessary minerals and water, and to promote organic substance to the desired part of the plant for their further storing.
- Protection seed pericarp structures, often thick-fleshed fruit.
- variety of methods of pollination (wind, insects, animals, birds, self-pollination, cross-pollination, and others).
- reproductive organs (gametophytes) are able to develop quickly and simply, are under the protection of the plant sporophyte.
- biochemical composition of tissues.Many members contain toxic substances, alkaloids, flavonoids, volatile, and so forth, which prevent them eating animals and not allow suppressing their growth of other plants.
- structure implies the existence of angiosperms in different life forms - trees, shrubs, bushes, shrubs, grasses, vines.
These distinctive features make this a very popular group of plants, hardy, well adapted and resettlement.As well as the necessary and important for man and his business.
Classification
There are over 250,000 species of angiosperms, united in the birth of 13 thousand 350 families.Systematics sufficiently numerous and representatives of taxa.
The classification is based primarily angiosperms classes, of which there are two:
- monocots;
- bipartite.
Each class is represented by a number of families, including various forms of life and in all common areas.
Class dicots
Includes angiosperms, examples of which almost everyone has at home in the form of potted flowers.It violets, begonias, spatifillyum, rubber plants.From gardening all Rosaceae and Solanaceae, Cruciferae and butterfly, Compositae - rose, tomatoes, cucumbers, potatoes, cabbage, grapes, eggplant, buckwheat and others.Among the wood forms also have flowering plants, examples of oak, ash, maple, linden, birch and so on.Representatives of economically important sources of valuable raw materials: cotton, flax, jute, Hevea, cinnamon, hemp, laurel and many others.
Total Dicotyledones has over 170 thousand. Species, representing approximately 75% of all flowering plants.In their classification includes 360 families, united in 60 orders from seven subclasses.
Distinguishing features bipartite
There are several key.
- presence in the semen of two cotyledons (halves).Especially well it can be seen on the example of the seed legumes.There are exceptions to one or cotyledons 3-4.
- type of root system: rod.It has almost all the data flowering plants.Examples, in which it is easy to trace: peppers, hemp, nettle, begonias, spinach and so on.Exceptions - in tree form.
- flower almost all four- or five-membered.Rarely different.
Class Monocotyledonous
has about 80 thousand different representatives, united in the family.Numerous valuable angiosperms, examples of which include the following: all the cereals, Liliaceae, Amaryllidaceae, Banana, Sedge, most palms.And that's not the whole list, because every family includes a large number of specific types of Representatives.
great value in the food industry people have cereals.These include the world's most cultivated crops: wheat, rice, barley, rye, corn and others.
The main features of monocots
There are several key:
- root system - fibrous, with a few exceptions;
- leaves lanceolate, elongated;
- flower tripartite rarely four- or two;
- cotyledon in the embryo alone.
classes of angiosperms and their numerous members formed the diversity and beauty of the surrounding flora, which is so nice to look at and that gives us life.That's because the plants produce oxygen, and without this gas none of the animals is not able to survive.
