. A manual of the medical botany of North America [microform]. Botany, Medical; Botany; Botanique médicale; Botanique. 24 ELEMENTS OF UOTANY. We have already seen thah leaves arc eonipoHed of cellular and woody tifisi:.., and have considered the latter in its raniilications whi(;h make up the leaf-skeleton. We will now briefly examine the cellular tissue. Unlike the cellular tissue of the stem, this is a gretiii pulp closely reseniLling the greou layer of the Lark. It is made u\i of cells somt^Lat loosely arranged, with oi)en spaces or air-passages between them (Fig. 35). These cells ovvo thei
. A manual of the medical botany of North America [microform]. Botany, Medical; Botany; Botanique médicale; Botanique. 24 ELEMENTS OF UOTANY. We have already seen thah leaves arc eonipoHed of cellular and woody tifisi:.., and have considered the latter in its raniilications whi(;h make up the leaf-skeleton. We will now briefly examine the cellular tissue. Unlike the cellular tissue of the stem, this is a gretiii pulp closely reseniLling the greou layer of the Lark. It is made u\i of cells somt^Lat loosely arranged, with oi)en spaces or air-passages between them (Fig. 35). These cells ovvo their green color to minute grains of a peculiar green coloring matter, termed chlorophyll, which they contain. Externally th(> entin; leaf is covered with a thin, transparent membrane, termed V^"^'^''"^— epidc mis (Fig. 3G); this is perforated Pig. . of a loaf, (.howhiK Kt,. y^^.{^]^ numerous openings, termed stomata nmta (;rL's). Magnitiud. i • , (iMg .W), winch iK'rmit the external an- to have free access to the interccUuhu" air-passages. The stomata arc nuich more numerous on the under than the upper side of the leaf, and here also the air-passages ax'e most abundant. FUNCTIONS OF THE LEAVES. Leaves have often been compared with the lungs of animals, since it is their office to aerate the vital fluids of plants. The nourishment collected by the roots is transmitted through the stem to the leaves, and here, ex- posed to contact with the «'L', it becomes elaborated and fitted for the plant's further use. Through the multitude of stomata, or breathing-pores, the air has free access to the interior of the leaf, where the cells take from it carbonic acid and yield up their superfluous moisture, or absorb oxygen and water as may be required. Li sunlight leaves absorb carbonic acid and give out oxygen ; in darkness the process is reversed and carbonic acid is exhaled. But as plants are much more active in daylight than in darknes
Size: 1626px × 1536px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1800, booksubjectbotany, booksubjectbotanymedical
