Tag: biology

Photonasty - the tendency in certain plant species to respond to light by developing sufficient cellular force or growth on one side of an axis to change the form or position of the axis, as in the opening and closing of the flowers of four-o'-clocks.

Haptonasty or thigmonasty is the non-directional movement of a plant part in response to the touch of an object. The closing of the lamina of Venus fly trap is a type of haptonasty as a result of contact with an insect. If an insect happens to cross the lamina, the leaf will close quickly to prevent its escape. 

Nastic movements are responses of plant parts to stimuli. Photonastic movement is the nastic response of plant in response to light. Thermonastic movement is the a nastic response of plant in response to change in temperature. Seismonastic movement is the nastic response of a plant to touch or vibration. Dropping of leaves of Mimosa pudica upon touching is due to seismonasty. Thigmonastic movement is the nastic response of a plant to touch. The movements of tentacles of Drosera when comes in contact with insect is due to thigmonasty.

Nastic movements are responses of plant parts to stimuli. Seismonasty is the nastic response of a plant to touch or vibration. Dropping down of leaves of Mimosa pudica upon touching is due to seismonasty. Nyctinasty is the rhythmic nastic movement of plant in response to the onset of darkness. Chemonasty is the nastic response of a plant to external chemical. 

Nastic movement is the movement shown by plant part in response to environmental stimuli. This movement is repeatable and reversible. Examples include the folding of leaves of Mimosa pudica when touched. The folding and recoiling of leaves of Mimosa pudica in response to touch is called as thigmonastic movement.

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.