. British plants : their biology and ecology. Plants; Plant ecology. INFLUENCE OF WATER ON PLANT-LIFE 27 and close the opening. This controlled or regulated diffusion of water-vapour through the stomata is called trans- piration. In a few cases water is actually expelled in liquid drops from the leaves. These emergency - exits are special openings (hydathodes ; Gr. hydatos, water ; hodos, way, channel), usually in the form of large stomata, always open. Plants which grow in an atmosphere constantly moist, such as exists in a tropical rain-forest, and to a lesser degree in damp lowland valleys
. British plants : their biology and ecology. Plants; Plant ecology. INFLUENCE OF WATER ON PLANT-LIFE 27 and close the opening. This controlled or regulated diffusion of water-vapour through the stomata is called trans- piration. In a few cases water is actually expelled in liquid drops from the leaves. These emergency - exits are special openings (hydathodes ; Gr. hydatos, water ; hodos, way, channel), usually in the form of large stomata, always open. Plants which grow in an atmosphere constantly moist, such as exists in a tropical rain-forest, and to a lesser degree in damp lowland valleys in this country, must get. Fig. 4.—Vertical Section of Part of a Leaf cut through a Stoma. (Highly Magnified.) a, stoma ; b, guard-cells ; c, epidermis ; d, cuticle ; e, air-cavity ; /, chloro- phyll-tissue. rid of their surplus water in this way, for the amount transpired is very small. The young leaves of most rapidly - growing herbaceous perennials also possess hydathodes. In these cases large quantities of water must be absorbed in order to supply adequate nourish- ment, but, at the same time, the surface through which water can be transpired is small. The only method by which the whole of the excess can be got rid of is by excret- ing it in a liquid form. The small white spots on the teeth of such leaves indicate the position of these hydathodes, and if they are examined in the early morning of a moist spring day, drops of water can be seen hanging from. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Bevis, James Frederick; Jeffery, Henry John. London : A. Rivers
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisher, booksubjectplants
