. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. DORSIVENTRAL LEAVES III The spongy cells also serve to conduct elaborated food-materials in various directions to the adjacent veins, a function to which the}' are ^^â ell suited bv virtue of their irregular shape. The structure of the mesophvl! just described is characteristic of dorsiveniral leaves generallv, the foUowing being the chief modifications. The palisade tissue not uncommonl\' consists of several layers ( Wallflower, Holh', Fig. 43, A), a feature especiall}' encountered in leaves exposed to s
. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. DORSIVENTRAL LEAVES III The spongy cells also serve to conduct elaborated food-materials in various directions to the adjacent veins, a function to which the}' are ^^â ell suited bv virtue of their irregular shape. The structure of the mesophvl! just described is characteristic of dorsiveniral leaves generallv, the foUowing being the chief modifications. The palisade tissue not uncommonl\' consists of several layers ( Wallflower, Holh', Fig. 43, A), a feature especiall}' encountered in leaves exposed to strong illumination, whUst leaves developed in dull light may have httle or no pahsade tissue. In some cases [ the House -leek) the assimila- torv* cells have quite a differ- ent form, being elongated parallel to the midrib, whilst in transverse section they appear more or less rounded. Plants grow- ing in ; sunny situa- tions often ex- hibit a second layer of colourless cells beneath the upper epidermis. The cells of this hypodenn (p. 95, Fig. 43, Hy.) are usuallv thick-walled, and consequently form with the epidermis a strong surface skin, besides further screening the underMng chloroplasts from excessive illumination. Variegated leaves usually exhibit a similar structure to that of the normal foliage of the same species, except that locahsed areas show no development of chlorophyll; these areas in con- sequence appear white or yellow. It need hardly be said that the structure of reduced fohage-leaves [ scale-leaves of rhi- zomes, bud-scales, etc.) is of a much simpler character. Such are. Fig, 53.âTransverse section through part of the leaf of the Elder (Sambucus) showing the upper epidermis (e.); â the arm-palisade cells [) ; the collecting cells {) ; and the spongy parench3-ma [). i., intercellular Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectpl, booksubjectplants
