Question

Which flower shows nyctinastic movement?
A. Albizia lebbeck
B. Pentapetes
C. Mimosa pudica
D. Bryophyllum

Answer 1

Hint: Spontaneous and induced are two types of movement in the plants. Spontaneous movement occurs without any external stimuli whereas induced movement takes place in response to outer stimuli.

Complete answer:
In response to external stimuli, plant movements are further divided into tactic, tropical and nastic movements.
Tactic movements are the changes in their locomotion due to any stimulus.
When some growth takes place in response to an external stimuli, it is a tropical movement.
Nastic movements are caused due to an external stimuli but the direction is not fixed. It is of two types: photonasty and nyctinasty.
1.Photonasty is the movement in response to light intensity.
2.Nyctinasty is the movement in response to darkness. Closing a flower at night or sleeping a plant are the responses to darkness.

Option A: Albizia lebbeck, common name: Siris, woman’s tongue. The flowers are white of this tree and its common use is fuel, wood and forage. It does not show nyctinastic movement. Therefore, this is the incorrect option.

Option B: Pentapetes: It is a flowering plant. Commonly called midday flower or noon flower. It does not show nyctinastic movements. Therefore, this is the incorrect option.

Option C: Mimosa pudica: This plant is used in pharmaceutical industries. Also called a sleeping plant or sensitive plant and it shows nyctinastic movement. Therefore, this is the correct option.

Option D: Bryophyllum: It does not show nyctinastic movement. Therefore, this is the incorrect option.

Hence, the correct answer is option (C)

Note: Movements or activities that take place on a twenty-four clock are said to be circadian rhythm. The activities which take place on a yearly basis are circannual rhythm. Eating, sleeping are circadian while some animals or plants reproduce once a year which is circannual.