Leaves213-page8

Leaves213-page8 - stomata that open at night rather than in...

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Leaves - 8 Xeromorphic Leaves Plants that live in arid environments are subject to drought, and often, intense sunlight. Such plants are called xerophytes. Water loss is a serious problem and xerophytes have modifications to minimize water loss. Thick cuticle The upper epidermis may be several layers thick. The palisade parenchyma may also be thickened. Veins may have bundle sheath extensions The lower epidermis may have several layers and a thickened cuticle. Deep invaginations of the lower epidermis layer, called stomatal crypts, are common. Crypts often have many hairs, which in the depression of the crypt create a microenvironment that is more humid. Stomata are located in the crypts. Some xeromorphic plants may have succulent leaves, and may have
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Unformatted text preview: stomata that open at night rather than in the daylight to minimize water loss. Nerium oleander , xs Pine leaf, xs Conifer Leaves (Needles) The needles of conifers have many of the same adaptations of xeromorphic leaves. Conifers predominate in areas that have long, cold winters and dryer summers. To survive, conifers are adapted to conditions of moisture stress. A typical conifer needle will have sunken stomata, often in channels on the lower surface, a thick cuticle, hypodermis layers, and, in addition, an endodermis surrounding the vein (or rarely, veins). As with other conifer organs, the leaves will have resin canals, lined with parenchyma....
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