. Elements of plant biology. Plant physiology. 338 THE WOODY STEM cells (Fig. 56, a), immediately below the epidermis, sometimes from the epidermis itself, occasionally in a deeper layer of the cortex, and fairly often in the pericycle. In roots the phellogen is nearly always formed in the pericycle. Each phellogen cell arises as the result of two rapidly following divisions of the living tissue cell in which it is formed, the two new parallel walls being tangentially. cork CTT) Fig. 56.—Cork formation: a, b. Beginning of phellogen in the outer- most layer of cortex ; ep., epidermis ; phe
. Elements of plant biology. Plant physiology. 338 THE WOODY STEM cells (Fig. 56, a), immediately below the epidermis, sometimes from the epidermis itself, occasionally in a deeper layer of the cortex, and fairly often in the pericycle. In roots the phellogen is nearly always formed in the pericycle. Each phellogen cell arises as the result of two rapidly following divisions of the living tissue cell in which it is formed, the two new parallel walls being tangentially. cork CTT) Fig. 56.—Cork formation: a, b. Beginning of phellogen in the outer- most layer of cortex ; ep., epidermis ; phel., phellogen. c. Seven layers of cork formed by phellogen below epidermis, d. Diagram of two cork cells showing the three layers of the wall (see text). directed and cutting out the phellogen cell between them (Fig. 56, b, phel.). The phellogen cell then continues to divide,cutting off a series of daughter cells on the outside, towards the surface of the stem, forming a regular radial row, and the walls of these are thickened, and be- come partially converted into corky substance (Fig. 56, c). The middle lamellae remain unchanged, the next layers. 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 Tansley, Arthur George, 1871-. London, George Allen & Unwin Ltd. ; New York, Dodd, Mead & Co
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectplantph, bookyear1922
