Tag: living world of plants - plant physiology

The dropping of leaves of Mimosa pudica shows thigmonastic movement upon touching. This dropping is due to the action potential which travels through the plant. The stimulus travels in the form of signaling molecules and hormones. These includes intracellular calcium, reactive oxygen species, ethylene hormone.

Autonomic movement is the spontaneous movement of the protoplasm due to internal stimulus. Autonomic movement of variation takes place due to changes in the turgidity of cells. The leaves of Desmodium gyrans shows jerky lateral movement due to turgor change which results in the alteration of osmotic content. A movement shown by a plant part in response to an external factor is called as paratonic movement. 

Nastic movements are responses of plant parts to stimuli. Photonastic movement is the nastic response of plant in response to light. Oxalis flowers open in the morning and close during evening because of photonasty. Phototropism is the growth of a plant part in response to light. Phototaxis is the movement of a plant part in response to light. Nyctinasty is the rhythmic nastic movement of plant in response to the onset of darkness. 

Movement of plant in response to heat is called as thermotaxis. Movement of plant in response to a touch stimulus is called as thigmotaxis. Example include zoospore in Oedogonium. Movement of plant in response to external chemical is called as chemotaxis. Movement of plant in response to light is called as phototaxis. Chlamydomonas shows phototactic movement. 

Cyclosis is also called as cytoplasmic streaming. It is the directed movement of cytosol and organelles. Rotational cyclosis is seen in Hydrilla. Sperm movement is induced by the change in intracellular ion concentration. Sperm motility is also induced by sucrose. Flagella is a locomotory organ that is seen in slime mould along with fungi, protozoan, etc. Slime mould shows flagellar movement. Chlamydomonas move towards the light.

Thigmonastic movement is the nastic or nondirectional movement shown by plant part in response to the touch or vibration. Plants like Mimosa and Albizzia shows thigmonastic movement. Oxalis shows photonastic movement. Drosera shows haptonastic movement.