Plant stem

A stem is the above ground axis of a vascular plant. The young stem develops in the germinating seedling from embryonic tissue known as the hypocotyl. Lengthening of the hypocotyl lifts the cotyledon(s), plumule (leaf precursor tissues), and terminal or apical meristem above the ground. The surface cells differentiate and mature into a protective epidermal layer. A few cells interior differentiate as chollenchyma, providing support to the young stem. Clusters of elongated cells appear — these are the provascular strands. The remainder of the stem consists of parenchyma cells: those lying between the epidermis and the provascular strands forming a cortex and those interior to the provascular strands forming a pith. Parenchyma radiating from the pith between the precursors of the vascular bundles are called pith rays.

Monocot stems

Vascular bundles are present throughout the moncot stem, although concentrated towards the outside. This differs from the monocot root that has a ring of vascular bundles and often none in the center.

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The shoot apex in monocot stems is more elongated. Leaf sheathes grow up around it, protecting it.

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Monocot leaves have continuous vascular tissue going down from a shoot or stem.This is most clearly evidenced when pulling apart the leaves of corn or grass; the leaf fibers continue down wrapped around the stem to it's base. This is true to some extent of almost all monocots, and is one of their traits that is more evolved than the older type, dicots.

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Monocots rarely produce secondary growth and are therfore seldom woody.

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The cotyledons are not pushed above ground in monocots as they are in dicots.

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