A bud is a condensed immature shoot that has a growing point surrounded by closely placed immature leaves. Buds can be terminal or lateral. The axillary bud is a type of lateral bud that develops in the axil of the leaves arising at each node. Aerial modification of the stem or buds includes tendrils, hooks, thorns, bulbil, and spines.
Thorns are stiff and sharp, which lost their growing point; it helps in reducing transpiration and protect plants from herbivores. Thorns are modified stem or bud structure which contain vascular bundle. Citrus, bougainvillaea, Duranta, pomegranate, Alhagi are examples of axillary buds or stem.
