. A textbook of botany for colleges and universities ... Botany. 572 ECOLOGY bearing surface (figs. 8ii, 812). In xerophylic and hydrophytic dicolyls and gen- erally in monocotyls, the side walls of the epidermis usually are straight on both leaf surfaces (fig. 804), though in Maranta and in various grasses there are wavy walls of striking regularity. In plastic species, waviness culminates in mesophytic conditions; increased and decreased transpiration each result in relatively straight lateral walls. Whether wavy walls have a role of impor- tance is not known, though they have been thought t
. A textbook of botany for colleges and universities ... Botany. 572 ECOLOGY bearing surface (figs. 8ii, 812). In xerophylic and hydrophytic dicolyls and gen- erally in monocotyls, the side walls of the epidermis usually are straight on both leaf surfaces (fig. 804), though in Maranta and in various grasses there are wavy walls of striking regularity. In plastic species, waviness culminates in mesophytic conditions; increased and decreased transpiration each result in relatively straight lateral walls. Whether wavy walls have a role of impor- tance is not known, though they have been thought to add to the strength of the epidermis and also to give a greater diffusion surface for substances passing from cell to Figs. 813, 814. — Appressed unicellular epidermal hairs from a scale leaf of the winter bud of the Norway maple {Acer platanoides): 813, a general view, as seen in longitudinal section; note the common orientation of the hairs, which is responsible for the silky aspect of the scale leaf; considerably magnified; 814, a single hair; highly magnified. Structural features of epidermal hairs.—" Pro- tective" hairs commonly are stiff, thick-walled structures, which often are dead and air-containing at maturity. They may be attenuated uni- cellular structures perpendicular to the leaf surface (as in Verbena or in Potentilla, fig. 914); more rarely they are parallel to the leaf surface and closely ap- pressed, their common orien- tation giving the leaf a silky aspect (as in Aster sericeus and in the bud scales of Acer platanoides, figs. 813, 814). Other hairs are similar but multicellular, occasionally being branched (as in the mullein, fig. 815). A woolly felt, made up of a dense tangle of long hairs more or less parallel to the surface, extends in various directions (as in the everlastings and cinerarias, figs. 816, 817).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability -
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1910
