Tag: movement in plants

Etiolation is a process in flowering plants grown in partial or complete absence of light. It is characterized by long, weak stems, smaller, sparser leaves due to longer internodes and a pale yellow colour called as chlorosis.  It increases the likelihood that a plant will reach a light source, often from under leaf litter, or shade from competing plants. The growing tips are strongly attracted to light and will elongate towards it.

Vernation is the formation of new leaves or fronds. Circinate vernation is the manner in which a fern frond emerges. As the fern frond is formed, it is tightly curled so that the tender growing tip of the frond is protected within a coil. At this stage it is called a crozier or fiddlehead. As the lower parts of  the frond expand and toughen up, they begin to photosynthesize, supporting the further growth and expansion of the frond. In case of many fronds, long hairs or scales provide additional protection to the growing tips before they are fully uncoiled. Circinate vernation may also be observed in the extension of leaflets, in the compound leaves of Cycads.

Daily movements of plants are a part of circadian rhythms. A circadian rhythm is a biological process that displays an endogenous entrainable oscillation of about 24 hours. These 24-hour rhythms are driven by a circadian clock, and they have been widely observed in plants, animals, fungi and cyanobacteria.

Rapid rotational movement of cytoplasm is due to increase in water content. Cytoplasmic streaming also called as protoplasmic streaming, the movement of the fluid substance within a plant or animal cell. The motion transports nutrients, proteins and organelles within cells. First discovered in the 1830s, the presence of cytoplasmic streaming helped convince biologists that cells were fundamental units of life.

Siesmonasty means a response to shaking. The best example is Mimosa pudica (Touch-me-not plant) which is the sensitive plant. Such, plants respond to stimuli such as touch, blow or mechanical shock by folding their leaflets and lowering their leaves. This effect is caused by a change in the turgidity of the leaflets brought about by the movement of water into and out of the parenchymatous cells of the pulvinus or swollen leaf base.

Turgor growth movements are types of movements brought about by changes in turgor pressure of the cells, causing the movement. These may be divided into two types-
(i) Autonomous or spontaneous and
(ii) Paratonic or induced.
Autonomous turgor movements do not require any stimulus and are observed in the Indian telegraphic plant - Desmodium gyrans. 

Plants do not move and have been evolved for stationary mode of life. However plants show several types of movements. For example, opening of a flower bud is an example of increased growth of the upper surface of a plant part (such as a leaf- vegetative or reproductive/ floral), resulting in a downward bending of the part. This type of movement is called epinasty.

A response of a plant, that causes movement independent of the direction of the stimulus is a nastic response. It is not a growth response, is reversible, and can be repeated many times. 

Phototactic movement is movement of organisms influenced by light. Low intensiti of light induces positive phototactic movement in algae.

Plants do not move and have been evolved for stationary mode of life. However, plants show several types of movements.