It would seem, plants are densely fixed in the soil and cannot move anywhere: immovability – one of distinctive properties of this kingdom. However bodies of a plant can be sensitive to factors of the environment and change the provision and the direction of growth.
To what factors of the environment plant roots are sensitive
Roots of plants are sensitive to terrestrial gravitation, the moisture which is contained in the soil and mineral substances and also oxygen distribution. Thus, are characteristic of root systems geo-, hemo-, hydro- and an aerotropism.
By gravity the root usually grows down no matter how to arrange the taking roots escape or the sprouting seed. If to put a sprout horizontally (for example, to turn a pot sideways), through some time the plant will direct a root down again. The stalk at the same time shows the return reaction and seeks to grow up, in the direction "from" terrestrial gravitation.
Chemotaxis is the movement of bodies of a plant towards chemicals necessary for them. So, roots need mineral and other nutrients, and they will involuntarily move there where it is more of them. Thanks to this ability of roots the granulated fertilizers can be very effective as roots will direct growth towards separate granules with nutrients, and the increased concentration of fertilizers near a root will provide their best comprehensibility.
Uneven distribution of water causes hydrotropism – emergence of bends of a root towards bigger moisture content.
What the arrangement of elevated escapes depends on
The arrangement of stalks and leaves in many respects depends on illumination conditions. At insufficient lighting the leaves can be displaced or bent by sheet scapes towards light. This feature is called phototropism.
Roots usually show negative phototropism and are bent in the direction "from" excessive light.
For increase in the area of a photosynthesizing surface the sheet plates are perpendicular to incident light. At the same time small leaves, as a rule, try to fill intervals between large that there were no excess gleams and opacity of a part of foliage. In the conditions of bad lighting it promotes the most effective use of solar energy.
The sensitivity to unilateral mechanical influences is characteristic of the curling and climbing plants.
Opening and closing of flowers depends on temperature, darkness and light. In heat the flowers usually reveal, and in cold are closed. Light influences different types of flowering plants differently: some of them reveal on light and are closed in twilight, and others open at nightfall. Predatory insectivorous plants (rosyanka, a bladderwort) react to mechanical irritations.