. Beginners' botany. Botany. larger, even if the tree should live a century. It is not quite inclosed, however, for the narrow layers of soft cells separating the bundles remain be- tween them (Fig. 78), forming ra- diating lines called medullary rays or pith rays. The Several Plant Cells and their Functions. — In the wood there are some parenchyma cells that are still with thin wralls, but have lost the power of di- vision. They are now storage cells. There are also. Pi an ^ a so Fig. 78. —Arrangement of Tissues in Two-year - old Stem of Moonseed. WOOd fibers Which A pith; /, parenchyma. The
. Beginners' botany. Botany. larger, even if the tree should live a century. It is not quite inclosed, however, for the narrow layers of soft cells separating the bundles remain be- tween them (Fig. 78), forming ra- diating lines called medullary rays or pith rays. The Several Plant Cells and their Functions. — In the wood there are some parenchyma cells that are still with thin wralls, but have lost the power of di- vision. They are now storage cells. There are also. Pi an ^ a so Fig. 78. —Arrangement of Tissues in Two-year - old Stem of Moonseed. WOOd fibers Which A pith; /, parenchyma. The fibro- - . , n j vascular bundles, or wood arc tniCK-WailcQ strands, are very prominent, with and rigid (h Fig. thin medullary rays between. Fig. 79. —Markings in Cell Walls of wood fibers. 76), and serve to support the sap-canals s/>, spiral -, an, annular; or wood vessels (or tracheids) that are formed by the absorption of the end walls of upright rows of cells; the canals pass from the roots to the twigs and even to ribs of the leaves and serve to transport the root water. They are recognized (Fig. 79) by the peculiar thickening of the wall on the inner surface of the tubes, occur- ring in the form of spirals. Sometimes the whole wall is thickened except in spots called//fr (g, Fig. 76). These thin spots (Fig. 80) allow the sap to pass to other cells or to neighboring vessels. The cambium, as we have seen, consists Longitudinal section of wall at o, showing of cells whose function is growth. These pit borders at *, *.. 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 Bailey, L. H. (Liberty Hyde), 1858-1954. New York, The Macmillan company
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Keywords: ., bookauthorbai, bookcentury1900, bookdecade1900, booksubjectbotany
