. Class-book of botany [microform] : being outlines of the structures, physiology, and classification of plants : with a flora of the United States and Canada. Botany; Botany; Plants; Plants; Botanique; Botanique; Plantes; Botanique. THB EPIDERMAL SYSTEM. .^'^\ . K^^'^^^"^ l^^ ^Mr^ //SS^-" LIBRARY, ^4. {{ JUL 2:^ CHAPTER IIli THE EPIDERMAL SYSTEM ,„„„%.2^TAR^^^ Includes the external covering of all herbaceous growths, viz., the epick-nnis, stoniata, hairs, glands, cuticle, etc., organs which in older stems give place to bark, 676. The epidermis (skin) consists of a layer of U!iited,
. Class-book of botany [microform] : being outlines of the structures, physiology, and classification of plants : with a flora of the United States and Canada. Botany; Botany; Plants; Plants; Botanique; Botanique; Plantes; Botanique. THB EPIDERMAL SYSTEM. .^'^\ . K^^'^^^"^ l^^ ^Mr^ //SS^-" LIBRARY, ^4. {{ JUL 2:^ CHAPTER IIli THE EPIDERMAL SYSTEM ,„„„%.2^TAR^^^ Includes the external covering of all herbaceous growths, viz., the epick-nnis, stoniata, hairs, glands, cuticle, etc., organs which in older stems give place to bark, 676. The epidermis (skin) consists of a layer of U!iited, empty cells, mostly tabular, forming a superficial membrane. It invests all plants higher than mosses, and all parts save the extremities, the stigma and rootlets. Its office is to check evaporation. 683. -aV X 5S4 582 6<^2, Cells of eiiidorniis with a stoma from leaf of Ilellobonis foetidiis. 583, Vertical .section of a stoma of Narcissus; a, cuticle. 5S4, Epidermis cells with stomata of Tradescantiii Vir- giiiica. 677. Example. That delicate membrane which may be easily stripped off from tlio leaf of ti)e liouseleek or the garden iris is the epidermis. It is transparent, color- less, and under the microscope reveals its cellular structure. 078. Stomata. The epidermis does not entirely exclude the tissues beneath it from the external air, but is cleft here and there by little chinks called stomata (mouths). Each sloma is guarded by a pair of reiiiform cells, of such mechanism (not well understood) as to open in a moist atmosphere and close in a dry. (579. Position of stomata. The stomata are always plar^ed over and communi- cate with tlie intercellular passages. They are found only on the green surfaces of parts exposed to the air, most abundant on the under surface of the leavea Their numbers are immense. On the leaf of garden rhubarb 5,000 were counted in the space of a square inch •. in the garden irib. 12,000; ia the pink, 36,000; in Hy- drangea, 160,000. j i m
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Keywords: ., bookcentury1800, bookdecade, booksubjectbotany, booksubjectplants
