. Plant life, considered with special references to form and function. Plant physiology. 70 PLANT LIFE. In both cases, the differentiation of cells produced at the growing jioint resulis in the formation of three characteristic parts (.)f the root, namely, (i) an outer layer or layers, the epidermis : (2) an inner region, the stele ; (3) between these, the cortex. 78. I. The epidermis usually becomes man\'-layered. At the apex it constitutes the rout-cap (ep, fig. 83). On the other parts of the root it sometimes sloughs off enlireU', exposing the cells of the cortex itself, as in the monocotyl
. Plant life, considered with special references to form and function. Plant physiology. 70 PLANT LIFE. In both cases, the differentiation of cells produced at the growing jioint resulis in the formation of three characteristic parts (.)f the root, namely, (i) an outer layer or layers, the epidermis : (2) an inner region, the stele ; (3) between these, the cortex. 78. I. The epidermis usually becomes man\'-layered. At the apex it constitutes the rout-cap (ep, fig. 83). On the other parts of the root it sometimes sloughs off enlireU', exposing the cells of the cortex itself, as in the monocotyledons (lilies, grasses, sedges, etc.); or, more commonly, only the outer layer sloughs off, leaving the innermost as the covering of tlie cortex. 79. [a) Eoot-hairs.—Those cells which form the surface of the root, whether they be the original epidermis or cortical ones which have been exposed by its loss, Usually de\elojj a large number of hairs, known as ruot-Iiairs ( fig. 84). These root-hairs are branches of the superficial cells (fig. 85), and may be looked upon as sim])le ex- tensions of them, as the finger of a glove is the extension of its palm. Only one root-hair arises from a superficial cell. Tlicy are usually unbranched and -without trans\-ersc partitions. Only in rare cases are they wanting. They lixe for a shorter or longer time, but are always, as compared with the duration ol the root, (juite transient. The older part of the. 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 Barnes, Charles Reid, 1858-1910. New York, H. Holt & company
Size: 1261px × 1980px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectplantphysiology
