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Coordination in plants

This kind of movement is shown by the the petals again open horizontally as seen
prayer plant (Maranta leuconeura) which in Figure 1.11. This process of changing
is an ornamental house plant. Prayer petal leaf position helps to conserve water
plant petals are horizontally open during and heat. Other examples of photonastic
the day to maximize its exposure to day movement can be observed in Dandelion
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active pollinators. At night, the petals fold flower (Taraxacum officinale), moon flower
vertically and appear like a pair of hands in (Ipomoea alba) and the flower of night
prayer. At sunrise the process reverses and blooming jasmine or Queen of the nights
(Cestrum nocturnum).

(a) (b)
Figure 1.11: Nastic movement in flower (a) during the day the flower opens (b)
during the night the flower closes
Chemonasty is chemonasty. The enzymes break down
This is a plant’s response to chemical the insect body into nutrients which are
stimuli. It includes inhibition of cellular absorbed. See Figure 1.12.
elongation and production of thick-walled
supporting tissue. Examples include the
chemical ethylene which inhibits growth
of certain crops and keeps them short and
bushy. Another example is when an insect
gets stuck on the leaves of a venus fly-trap
(Dionaea muscipula). As the insect gets in
touch with the sensitive trigger hairs on the
inner surface of the leaf lobes, it produces
signals which rapidly changes the turgor
pressure in the leaf cells. This causes the
leaf close and trap the insect which is an
aspect of thigmonasty. However, presence
of organic nitrogen compound released
from the trapped insect stimulate the
plant to secrete digestive enzymes which Figure 1.12: Chemonasty in plant

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