Question

Give examples of 3 plants that have: leaves which close at night.

Answer 1

Hint:Nyctinasty refers to the nastic movement of the leaves or petals of the plants in response to darkness. These movements are independent of growth and are a part of circadian rhythm that occurs in a 24 hour cycle.

Complete answer:
Nastic movements in plants are reversible and repeatable movements in response to the stimuli, the direction of which is determined by the structure of the plant. Many plants move their tendrils, flowers, or leaves in response to stimulus. Plants whose leaves open and close in response to day and night cycles are known as nyctinastics.

Nyctinasty is distinct from the tropical movement. Tropism is the movement or growth response of a cell or organism to a stimulus that can be either positive or negative based on the cause and form of stimuli. In other words, the tropism is related to the growth response of the plant to the stimulus. Phototropism, for example, is a type of tropism in which plants expand towards the source of light. In nyctinasty, certain plants are able to take a position at night that is different from their position during the day. This is a biochemical rhythm, as this action is repeated every circadian day. The sleeping position of these plants is said to be correlated with pulvinar movement, circadian clock, and light signal transduction via phytochrome. Three plants that close their leaves at night are Oxalis, Maranta and Acacia.

Note:Pulvinary movement involves pulvinar cells at the base of the plant leaf or at the apex of the petiole, which promote nyctinastic and nastic movements in a mechanism close to that of the stomatal closure.