Tag: movement in plants

In Funaria, 32 peristomial teeth are present. It consists of two sets of long, conical teeth, one within the other. There are 16 teeth in each set. It follows hygroscopic path where moisture is absorbed or attracted from air.

Hygroscopic movement is that, which is caused by changes in moisture content of unevenly thickened cell walls. E.g., elators or the awns of the grains of some grasses. Also hygrometric movement, imbibitional movement.

Nastic movements are non-directional responses to stimuli and are usually associated with plants. The movement can be due to changes in turgor or changes in growth. Nastic movements differ from tropic movements in that the direction of tropic responses depends on the direction of the stimulus, whereas the direction of nastic movements is independent of the stimulus's position.

Nutation is the bending movements executed by some plant organs such as stems, leaves, roots, etc, by which the part is inclined successively in various directions. Nutations are due to unequal rate of growth of different sides of the organ. Nutational movement includes all the movements in plants caused by growth in contrast to variation movements or movements produced by reversible turgor changes.

The definition of photomorphogenesis is any change in form or function of an organism occurring in response to changes in the light environment. Photomorphogenesis is often defined as light-regulated plant development, but there are also changes in morphology and/or cell structure and function, which occur as transient acclimatizations to a changing environment, which are also light regulated.

The free type of movements induced by some external stimuli like light, temperature, chemicals, etc are called as tactic movements. They are of three types: Phototactic, chemotactic and thermotactic.

The movement of chloroplasts in palisade cells in response to light is called as phototactic movement. Phototaxis is the movement of an organism in response to light; that is, the response to variation in light intensity and direction.

Desmodium gyrans is also called as 'Indian telegraph plant' which is a dancing plant. The movement in this plant is called as movement of variation. It is not categorized into nastic or curvature movements.

If the movement of curvature exhibited by plant organs is due to some external stimuli (caused by light, temperature, gravity, foreign bodies, etc), it is called induced movement of curvature. There are several spontaneous movements of curvature like Nastic movements, nutation, etc. Opening of sunflower is due to the light radiation of the sun. So it is an example of photonastic movement. Seismonasty is induced by movement by touch, shock, rain, wind, etc. Example: the leaves of plants Mimosa pudica and M.spegazzinii. All these are included in movement of curvature.

Growth movements are brought about by the unequal growth in different regions of the same organ. If shoot growth occurs at a faster rate alternately on right and left sides of the axis, resulting in a zig-zag axis, the movement is said to be nutation. When the leaves mature in growth and the flower buds open, more rapid growth occurs on the upper surface. This results in unfolding of coiled leaves and opening of the flowers. These are categorised under autonomic movement of growth.