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Q.
The aerial stem modification found in Bougainvillea
NTA AbhyasNTA Abhyas 2020
Solution:
Aerial modification of the stem includes tendrils, hooks, thorns and spines. Tendrils are thread-like sensitive structures that can coil around support and help the plant with weak stems to climb as in gourds and grapevines. Spines are modified leaf or leaf parts as in Opuntia. Hooks are modifications observed in Bignonia for hanging and attachment.
Thorns are the modified aerial stem structures. These are stiff, pointed, straight, hard, and sharp structures that have lost their point of growth. Thorns are basically formed to protect the plants from grazing and excessive transpiration. These structures have a vascular system surrounded by a bark of thick-walled cells. Example, Bougainvillea, citrus, etc.
