Group angiosperm representatives of the florait is customary to divide into monocotyledonous and dicotyledonous plants, which differ chiefly in the structure of the embryo. Nevertheless, these plant classes have other differences in the structure of the vegetative and generative organs.
Class Dicotyledons, or Magnoliosps: the structure of plants and their brief characteristics
To date, this class is considered quite large, as it includes about 200 thousand species. Its representatives have a number of very characteristic distinctive features.
Dicotyledons are represented by different forms- this is trees, bushes, and grass. In woody species within the stem there is a fairly powerful layer of cambium - a special tissue that ensures its growth in width. The leaves of plants can be either simple or complex, but practically in all species they are cuttings - sessile leaf blades are not characteristic for this class. The venation of the plate is in most cases mesh. The root system is predominantly pivotal - it has a main, main root, from which grow lateral, small in size.
Another feature is the structure of generativebodies. Most species have large flowers with a bright color. They have a double perianth (sepals and petals), flowers predominantly five- or four-membered. Dicotyledons are most often pollinated by insects.
And, of course, very characteristic is the structure of the embryo, which has two lateral cotyledons. By the way, the name of the class is connected with this feature.
Dicotyledons: the most common species
This class includes a huge number of species that are included in several thousand genera and three hundred families. The most famous of them are the following.
Family Cruciferae - representatives of hisare distributed mainly in the northern hemisphere of the planet. Most of its species are herbaceous forms or small shrubs. Everyone knows such representatives of cruciferous, as cabbage, radish, horseradish, turnip, mustard and radish.
The Pink family unites trees, shrubsand herbaceous plants, which are mainly distributed in temperate or subtropical climates. For example, all known rose hips and ornamental roses belong to this group. This includes most of the fruit trees and bushes, including apple tree, pear, cherry, mountain ash, raspberry, bird cherry, blackberry.
The family of legumes is its woody forms andshrubs are distributed mainly in tropical and subtropical countries, and herbaceous prefer a more temperate and even cold climate. All representatives of the group are characterized by a specific aureole of the "butterfly" type. This group includes the following known plants: peas, beans, alfalfa, beans, soybeans. By the way, some species actively participate in the nitrogen cycle.
Class Monocotyledons: a brief description
This group is represented predominantlyherbaceous plants - trees and shrubs in it are extremely rare. Their stems, as a rule, do not contain cambium and, therefore, are not capable of growth in thickness. Sheets are simple, with solid edges. They do not have a petiole and are attached to the stem by the edge of the leaf blade, because of what they are called sedentary leaves. The venation is in most cases parallel or arcuate.
Another feature is the furry root system, in which there is no main root. In the bud there is only one cotyledon, as the name of the class indicates.
Most of the monocotyledons are pollinated by wind. Therefore, their flowers - small, dull, with a single perianth, mostly trinomial.
Typical representatives of this group are cereals: wheat, oats, corn, rice and others.
