DescriptionAngiosperm Morphology the Xerophytic Monocotyledonous Leaf of Ammophila (37123165631).jpg
cross section: Ammophilia leaf
magnification: 40x
During periods of drought the leaves of the beach grass, Ammophila, temporarily curl to form a series of ridges and deep groves in the adaxial surface. The adaxial epidermis is uniseriate and lightly cutinized with large globular epidermal cells that occasionally extend into long needle like hairs. The outer and fully exposed abaxial epidermis is uniseriate and heavily cutinized.
Most stomata are located half way down the walls of the V shaped adaxial grooves. When water is abundant the large white buliform cells at the base of the grooves absorb water, become turgid and unroll the leaf.
A single large vascular bundle, bound by a bundle sheath and wrapped in heavy walled sclerenchyma, is located in the center of each ridge. The sclerenchyma extends from the apex to the base of each ridge to merge with the continuous ring of sclerenchyma that forms the abaxial hypodermis.
The vascular bundles are collateral and closed with xylem of vessels and tracheids towards the adaxial surface and phloem of sieve tubes and companion cells towards the abaxial surface. Cambium is not present.
Just deep to the epidermis, an unspecialized mesophyll of round chlorenchyma cells extends up each side of the ridge bundles and down and across the base of the grooves.
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