Anatomy of Monocot Stem - Maize

A maize stem - the monocot comparison - abandons the dicot stem's careful three-way cortical zoning almost entirely. Its hypodermis is sclerenchymatous rather than collenchymatous (there is no ongoing elongation to accommodate, so rigid support is laid down immediately rather than flexible support). Its ground tissue is not differentiated into cortex, endodermis, pericycle and pith at all - it stays one continuous mass of parenchyma from just under the hypodermis to the centre of the stem. There is consequently no starch sheath and no medullary rays, since neither a true endodermis nor a ring of separated bundles exists to define them. The vascular bundles themselves are conjoint and collateral like the dicot stem's, but closed (no cambium between xylem and phloem) rather than open, and instead of sitting in a single ring around a pith they lie scattered through the ground tissue with no consistent radial pattern - each individually wrapped in its own sclerenchymatous bundle sheath for support. The knock-on consequence of a monocot stem having no cambium anywhere - neither between its …