Question

Write two examples of plants with thorns.

Answer 1

Hint: In botany, thorns are referred to as spinose structures. Thorns are modified structures of stem. The various parts of plants like roots, stem leaves undergo modification to assess the function of food storage, protection, support, and defense mechanism.

Complete answer: Thorns, spines and prickles are called spinose structures. They are rigid hard extensions or modified roots, stems, or leaves. They normally have stiff ends and serve the purpose of deterring the animals from consuming the plant material. Thorns are derived from the shoot. They are modified stems that are present in the axil of leaves or the apex of the stem. The primary function of the thorn is to deter herbivores in a mechanical form. Thorns can be in the form of simple or branched. Some of the examples of plants which show the presence of thorns are Bougainvillea, Duranta, and climbing Rose.
Additional information:
The leaves, stipules, or parts of leaves are modified into spines. Spines are further described as petiolar spines, leaflet spines, and stipular spines. The plants belonging to the cactus family have spines to regulate the rate of transpiration and also act as a defensive mechanism. Opuntia is a xerophytic plant which has spines in them to control the transpiration rate. Xerophytic plants grow a very less amount of water or without water.

Note: Thorns of the plants arise from the bud. Both thorns and spines are classified by the presence of vascular tissue within them. Prickles do not possess vascular tissues inside them and hence can be removed easily. An example of a prickle is a rose prickle.