The cortex of a young stem is usually green, and plays a more or less important part in the assimilative function.
The whole cylinder is enclosed by the peculiarly differentiated innermost cell-layer of the cortex, known as the endodermis.
The inner layer of the cortex (phloeoterma) may form a well-marked endodermis, or differ in other ways from the rest of the cortex.
In some forms other gaps (perforations) appear in the vascular tube placing the pith and cortex in communication.
In both stem and root early walli separate the cortex from the stele.