A group of angiosperm plants has formedmore than 125 million years ago. And there are still disputes about a specific period (era) of their occurrence. Some call the Cretaceous period, others talk about earlier dates, and others say later.
Несомненным остается одно:This category of plants occupied a dominant position and settled absolutely on all parts of the globe, ranging from tropical rain forests and ending with hot and icy deserts of Africa and the Arctic.
What are they, angiosperms? Examples, signs and properties of taxon, classification, consider below.
Angiosperms: General Characteristics
Свое название представители данной группы received for the ability to cover the seeds with soft or hard tissue of the fetus. After all, in place of a flower, which is a taxon's business card, a variety of structures are formed in shape and size, color and nutritional value. They are called fruits.
Само растение - это побег, уходящий в землю root system and having a flower, stem and leaves. A reproductive organ characterized by a special structure and allowing it to adapt to any habitat and conquer new territories for settlement - this is the flower.
Более прогрессивное строение, появившиеся в ходе the evolution of features and adaptations made it possible to oust representatives of gymnosperms, bryophytes, and ferns. Today, in the flora of our planet, beautiful, bright, diverse in life forms angiosperms dominate. Examples can be given for a very long time, because there are more than 13 thousand births here. In short, you can say this: all plants with a flower are angiosperms.
General plan of the building
The main organs that each hasA representative of this group are those that are characteristic of all higher plants: root, stem, leaves. An additional structure that provided the angiosperm with the ability not to depend on water for the reproduction process was the flower.
Parts of a flower:Stipules, receptacle, pedicel, corolla of petals, ovary, pistil, pistil stigma, stamens. All of these structures are important as reproductive organs, as well as those that are later converted into a fruit that protects the seed until full maturity.
People appreciate plant flowers for their extraordinarybeauty and tenderness, pleasant aroma. Use their healing properties, extracting useful extracts, grown in order to obtain in the future juicy and tasty fruits.
For the plants themselves, the flower is a useful important.the organ that saved them from water dependence during reproduction, because now it is done with the help of double fertilization. Fruits give protection and protect the seeds, as well as participate in their dispersion when eaten by animals, this is also a big plus, distinguishing the structure of angiosperms from other plants.
The different structure of flowers, the variety of their forms allows to increase the methods of pollination, which also contributes to the wide distribution and dispersal of plants.
Features
Of course, the most important and reliable innovation forFlowering has become a flower formation. However, not only this, but also other signs of angiosperms favorably emphasize and confirm their massive predominance among representatives of the flora. Such, for example, as:
- Presence of more perfect conducting system,including sieve-like elements of phloem and phloem tissue. This allows you to more quickly transport the necessary minerals and water, as well as promote organic matter to the desired parts of the plant for the purpose of their further storage.
- Protection of the seed structures of the pericarp, often with thick fruit pulp.
- Variety of pollination methods (wind, insects, animals, birds, selfing, cross-pollination, and others).
- Reproductive organs (gametophytes) are able to develop quickly and simply, are under reliable protection of the sporophyte plant itself.
- Biochemical composition of tissues.Many representatives contain toxic substances, alkaloids, flavonoids, phytoncides, and so on, which prevent animals from eating them and prevent their growth from being suppressed by other plants.
- The structure of angiosperms implies their existence in different life forms - trees, shrubs, shrubs, dwarf shrubs, grasses, vines.
Such distinctive features make this group of plants very popular, durable, adapted and widely settled. And also necessary and important for the person and his economic activities.
Classification
There are over 250 thousand species of angiosperms, united in 13 thousand genera from 350 families. Systematics is quite numerous in taxa and representatives.
The classification is based primarily on classes of angiosperms, of which there are two:
- monocotyledonous plants;
- dicotyledonous.
Each class is represented by a number of families, including different life forms and common in all territories.
Class Dicotyledonous plants
Includes angiosperms, exampleswhich almost everyone has at home in the form of potted flowers. These are violets, begonias, spathiphyllum, rubber plants. From garden and garden all Rosaceae and Solanaceae, Cruciferous and Butterfly, Compositae - rosehip, tomatoes, cucumbers, potatoes, cabbage, grapes, eggplant, buckwheat and many others. Among the tree forms there are also flowering plants, examples: oak, ash, maple, linden, birch and so on. Economically important representatives, sources of valuable raw materials: cotton, flax, jute, hevea, cinnamon, hemp, laurel and many others.
In total, Dicotyledons number over 170 thousand species, which is approximately 75% of all flowering ones. Their classification includes 360 families, united in 60 orders from 7 subclasses.
Distinctive Signs of Dicots
There are several main ones.
- The presence in the seed of two cotyledons (halves). Especially well it is possible to look at the example of the seed of legumes. There are exceptions with one or 3-4 cotyledons.
- Type of root system: rod.Almost all these flowering plants have it. Examples on which it is easy to follow are: pepper, hemp, nettle, begonias, spinach, and so on. Exceptions are for tree forms.
- The flower of almost all four or five members. Rarely different.
Monocot class
It has about 80 thousand differentrepresentatives united in families. Valuable angiospermous plants are numerous, examples of which can be cited as follows: all Cereal, Lily, Amaryllis, Banana, Sedge, most palm trees. And this is still not the whole list, because each family includes a large number of specific species representatives.
Grains are of great value in the human food industry. These include the most cultivated crops in the world: wheat, rice, barley, rye, corn and others.
The main features of Monocots
There are several key ones:
- root system - fibrous, with rare exceptions;
- leaves lanceolate, elongated;
- three-membered flower, rarely four or two;
- seedbed in embryo one.
Grades of angiosperms and theirNumerous representatives form the diversity and beauty of the surrounding flora, which is so pleasant to admire and which gives us life. That's right, because plants produce oxygen, and without this gas, no animals can live.
