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Plant Body Structure

 

Plants are complex living organisms, consisting of interrelated and coordinated working bodies - the roots, stems, leaves and flowers, of which then formed the fruits and seeds.

Roots, stems, leaves - vegetative organs and flowers, fruits and seeds - reproductive organs, t. E. Generative. Roots perform two important functions: to strengthen plants in soil and food, t. E. Is removed from the soil necessary for living water and dissolved nutrients, guiding them through the stem to the leaves. T

Plant - complex living organisms, consisting of interrelated and coordinated working bodies - the roots, stems, leaves and flowers, which are produced from fruits and seeds.

Roots, stems, leaves belong to the vegetative organs and the flowers, fruits and seeds to the reproductive organs, t. E. To the reproductive organs.

 

Vegetative organs

The main vegetative organs already laid in the bud seed. With the advent of favorable temperature and humidity conditions seeds absorb water and sufficient air germinate. First start to grow root that breaks spermoderm and introduced into the soil. With this young seedling in soil strengthening and absorbs water with dissolved salts. Following the root starts to grow escape. At first, he bent and pushes its soil bend, then straightens and makes the surface of the cotyledon and kidney. Cotyledons are green and some time the function of leaves. Kidney also continues to grow upwards, forming the stem and the first true leaves, which have a different shape than the leaves of adult plants (juvenile leaves). The boundary between the root and the stem is called the root neck.

In cereals, along with the main root in the basal part of the stem immediately formed adventitious roots. Upon germination single cotyledon remains in the soil and absorb nutrients endosperm. Breaks through the soil kidney protected embryonic leaf - coleoptile. The first true leaf out through breakthrough coleoptile.

 

Root

Root is a underground organ. With its help, the plant is strengthened in the soil absorbs water from it and dissolved minerals, which are then fed to the above-ground part of the plant. The root serves as a replacement deposits of nutrients, as well as the body may be due to breeding adventitious buds are formed on it.

Education of the root system, ie. E. The set of all roots, begins with the growth of the embryonic root seed from which first develops the main root. Lateral roots that extend directly from the main (central) root names roots of the first order. They depart from the roots of the second order, and so on. D.

Each plant has a selective absorption of salts from the soil solution. Different types of soil removed varying amounts of the same salts. This is one of the major reasons that it is impossible for a number of years to cultivate the same place any one culture.

Plant roots are diverse in form. Rod - legumes, fibrous - cereals, roots - carrot, beets, tubers - potato rhizome - couch.



 

Stalk

Stalk is the aerial part of the plant, which together with the lateral shoots (branching) form its skeleton, or framework, connects the roots. system and leaves, bears buds, leaves, flowers and fruits. Stalk - conductor of water, mineral and organic. substances. Simplistically current pit. stem substances can be represented as follows.

By vessels located close to the center of the stem, the pit. substances move from the root system. in leaves t. e. from the bottom up. The vessels close to the outer part of the stem, on the contrary, -from leaves to flowers, fruits, buds, roots.

Part of the stem - woody cuttings and green - can be used for vegetative propagation. Many plants have modified stems - bulbs, rhizomes, and so on. E., Which are also used for breeding.

 

Leaf

Leaf is the most important organ of the plant. Its main feature - photosynthesis. In some cases it may be organ reproduction. In many plants the leaves are laid spare pit. substances and succulents (from Lat. sukkus -sok, sukkulentus -sochny - plants have thick, fleshy aerial organs) are stored in the moisture. Sheet regulates gas exchange of the plant.

Sheet plays a significant role in human life. Good leafy plant dampens noise, collect dust and others. The weighted particles in the air, and many foliage plants emit volatile substances (volatile - Gr. Fiton -rastenie, Lat. Tsedere -ubivat) killing disease-causing microbes (calendula, balsam poplar, arborvitae, spruce).

Sheet is formed from the primary tubercles of the growing stem. It consists of a stem and lamina. Some plant species are different in size and shape stipules.

If the leaves are attached to the stem stem, they names petiolate, leaves attach to the stem base of the leaf blade, called sedentary order of attachment of leaves on the stem names leaf arrangement. At the next sitting Phyllotaxy leaves on the stem of one alternating al. With others. When opposite leaf arrangement on the stem leaves are placed on the two against each other. When whorled leaf arrangement leaves attached to the stalk bundles - whorls.

In the process of photosynthesis produced organic compounds - carbohydrates and releases free oxygen. In the future, carbohydrates are converted into more complex compounds - proteins, fats, and so on. E., That go to form the vegetative organs of plants and the formation of flowers, fruits, seeds.

Reproductive organs

Flower is a modified short shoots, adapted for the formation of micro and megaspores, gametes and cross-pollination. As a result of pollination and subsequent sexual reproduction (fertilization) formed seeds and fruits.

Megaspore is a dispute that gives rise to the female gametophyte: in seed plants from megaspore developing embryo sac.

Structure. The stem of the flower pedicel and receptacle provided. Receptacle can take many forms - from conical to flat or even concave in the form of glass. Receptacle placed on modified leaves (color leaves): sepals, petals, stamens, pistils.

The distribution of the sexes. Flowers with stamens and pistils and called bisexual (androgynous). Dioecious flowers or contain only stamens or pistils only. Plants with staminate and pistillate flowers on a single instance called monoecious. Plants in which some items are only staminate flowers, and others - only pistillate called dioecious.

Corolla

Usually consists of different stained petals. Petals can coalesce with each other, at least in part, or to remain free

If all the petals of the corolla of the same size and shape and are arranged symmetrically (apart from the center like rays), then whisk and flower is called regular or actinomorphic. Through this flower can spend a few planes of symmetry (apple, cabbage). Incorrect or zygomorphic, called flower, through which you can draw only one plane of symmetry. Corolla lobes him different in shape and size (black locust, bean). Flowers, through which you can not spend a single plane of symmetry, called asymmetric (valerian, eland, orchids). The shape of the corolla campanulate may be (lily of the valley, a bell),), tubular (sunflower), Reed (dandelion), bilabiate (dead-nettle).

Tasks

Math the words with their correct definitions

Flower is the most important organ of the plant. Its main feature - photosynthesis.
Leaf is a modified short shoots, adapted for the formation of micro and megaspores, gametes and cross-pollination
Stalk is a underground organ.
Root is the aerial part of the plant

 

 

Topic 9

Regulatory systems

Endocrine system - a system of regulation of the internal organs through hormones secreted by endocrine cells directly into the blood, or diffusing through the intercellular space in the neighboring cells.


Date: 2015-12-11; view: 168


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