Stems and branches are the above ground parts of the plant axis and bear leaves, buds, flowers at nodes. The internal structure of stem at the nodes and at internodes differ slightly due to the above reasons.
In general, a stem is characterised by the following internal organisations:
(i) Epidermis is with or without hairs but when epidermal hairs are present, they are multicellular or unicellular.
(ii) Hypodermis is present either in a continuous or discontinuous manner.
(iii) Vascular bundles are conjoint, collateral or bicollateral, and endarch with centrifugal development of xylem.