Shoot Apex

Shoot apex is the terminal, dome shaped part of shoot, formed of meristem called apical shoot meristem responsible for the development and differentiation of primary permanent tissue and mainly causes growth in length. It is divided into two regions - Tunica and Corpus.

Tunica (covering)

An outer zone of shoot apex, 1-3 layers in thickness. It gives rise to epidermis and is responsible for surface growth, and its cells divide only anticlinally.

Corpus (body)

Inner multi-layered zone of cells which divide in all directions. They finally give rise to procambium (forms vascular tissue) and ground meristem (forms ground tissue). These cells also form leaf primordia (a newly developing leaf).

Origin of Lateral Branches

Branches arise from axillary buds present in the axil of leaves. Each axillary bud is a small, compact, underdeveloped shoot covered with a large number of overlapping leaf primordia. Internodes of this bud enlarge and develop into a branch. Therefore the development of branches is exogenous (exo means outside).