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Ordinary epidermis
Guard cells
Thick cuticle
Thicker cuticle
Thin cuticle
Parasitic plant
Petal epidermis
Sclerified epidermis
Papillose epidermis
Sculptured cuticle
Elaborate cuticle
Cuticular horns
Radial walls
Cuticle proper
No epidermis
Epidermal peels
Cycad peel
Paradermal
Typical stoma
Sunken stoma
Stomatal orientation 1
Unusual orientation 2
Artifact
Stomata and fibers
Stomatal crypts
Crypts, mag.
Crypt margin
Non-crypt
Water lily
Stomatal channels
Groove, hi mag
Subsidiary cells
Ledges
Papillae
Trichome
Uniseriate hair
Peltate hair, mag
Peltate, lo mag
Branched hairs
Trichome base
Lithocyst, Ficus
Lithocysts, hemp
Bulliform cells
Grass epidermis
Multiple epi
Uniseriate?
Peperomia

Fig. 10.3-9. Transverse section of corn stem (Zea mays). Stems of corn, like those of many monocots, have a very fibrous construction. Here, the vascular bundles are enclosed by bundle sheath fibers and the outermost cortex consists of several layers of fibers. Most fiber tissue is compact, with few or no intercellular spaces, which inhibits the diffusion of gases. Notice that the band of fibers in the outer cortex is interrupted near the stoma: just below the stoma is a mass of blue-stained parenchyma cells with intercellular spaces. It is not quite open enough to call it an aerenchyma, but it does permit carbon dioxide to pass through the epidermis and be absorbed by the chlorenchyma in the cortex.

            How is this controlled? Does the initiation of guard mother cells prevent the formation of fibers? Or does the fibrous cortex leave gaps in itself, and those gaps stimulate the differentiation of guard mother cells?