Monocotyledonous plants - a class of department floral. The name was received by quantity of cotyledons in a germ. Are generally presented by various herbs. There were monocotyledonous plants about 110 million years ago.
About origin of monocotyledonous plants
A consensus about origin of monocotyledonous plants among scientists is not available. Generally it is considered that monocotyledonous plants occurred from protozoa bichromatic. Bichromatic is the second class of flowering plants. As proof to it families of monocotyledonous and bichromatic plants have a number of the general signs. On the other hand, monocotyledonous arose almost along with bichromatic. The closest ancestors of monocotyledonous plants most likely were land, well transferring a humid climate. They grew on swamps and on coast of the rivers and lakes. Therefore other view of origin of monocotyledonous – from primitive grassy plants.
Main features of the building
Representatives of monocotyledonous plants are far not so numerous as bichromatic. However among them the big percent is carried to the cultural plants used by the person in the industrial purposes. Monocotyledonous plants have a number of characteristic signs. The main of them which gave the name to all class – presence of one cotyledon at a germ. Sprouts a germ podzemno, forming bulbs and the developed rhizomes. Veins on a leaf are located in parallel, is more rare – arcuately, form the closed drawing. The leaf is not divided into a scape and a plate, and kind of covers a stalk.
The carrying-out system of a stalk is presented by several not connected bunches or rings of bunches which are located chaotically. These bunches are deprived of a cambium, the layer of fabric providing growth in width. There is no cambium as well in stalks therefore monocotyledonous do not grow in width. There is no accurate distinction of bark and a core of a stalk. The germinal back after germination dies off early, from it the main root, as at bichromatic does not develop. Instead of it the system of additional roots is formed. Therefore the root system monocotyledonous is called mochkovaty. Monocotyledonous plants can be presented by the following vital forms: herbs and secondary treelike forms. Initially wood monocotyledonous do not exist. Most often it is annual or biannual plants. Flowers at monocotyledonous most often tripartite, are more rare four-membered or dvukhchlenny. They gather in inflorescences. At bichromatic flowers five-membered. The most widespread type of a fruit – a box, is more rare – berry. The cover of pollen grains – odnoborozdny, a stalk does not branch, upright. About 70 families of monocotyledonous plants, the most known of them – lily family, cereals are known.