Question
Discuss the types of nastic movements with examples.
Answer
Nastic movements are non-directional, reversible plant responses to external stimuli like light, temperature, or touch. There are several types of nastic movements, including:
- Photonasty: This movement is in response to light. An example is the opening and closing of flowers. The petals of certain flowers, like the morning glory, open in response to light in the morning and close at night.
- Thigmonasty: This movement occurs in response to touch or mechanical stimuli. For instance, the sensitive plant (Mimosa pudica) folds its leaflets when touched, as a defense mechanism against herbivores.
- Seismonasty: This is a rapid thigmonastic response triggered by touch or mechanical disturbance. The Venus flytrap closes its trap rapidly when an insect touches its trigger hairs to capture prey.
- Thermonasty: This movement is related to changes in temperature. For example, the petals of certain flowers may open during the day when it’s warmer and close at night when temperatures drop, as seen in tulips.
- Nyctinasty: Nyctinastic movements are rhythmic, diurnal movements that occur in response to the daily light-dark cycle. Examples include the closing of petals in certain flowers at night and their reopening in the morning.
