. Beginners botany. Botany. THE STEM—ITS GENERAL STRUCTURE 65. 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. 'jZ), 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 have b thin walls still, but have lost the power of di- vision. Thev are R] an I ^ ^=!^ ^ now storage cells. ^^^- 78. —arrangement op ™, Tissues in Two-year- mere are also old stem of moonseed. wood fibres
. Beginners botany. Botany. THE STEM—ITS GENERAL STRUCTURE 65. 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. 'jZ), 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 have b thin walls still, but have lost the power of di- vision. Thev are R] an I ^ ^=!^ ^ now storage cells. ^^^- 78. —arrangement op ™, Tissues in Two-year- mere are also old stem of moonseed. wood fibres which /, pith; /, parenchyma. The fibro- are thick-walled -scular bundles, or wood strands, are very prominent, with Fig. 79. — Markings and rigid (h, Fig. thin medullary rays between. IN Cell r7a\ 1 . .i i OF Wood Fibre '^j, and serve to support the sap-canals J/, spiral;««, annular; Or wood vessels {ov traclieicls) that are .ff, scaianform. 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 ///J (^, Fig. y6). These thin spots (Fig. 80) allow the sap to pass to other pj^,_ 80. —pits in cells or to neighbouring vessels. the Cell Wall. The cambium, as we have seen, consists Longitudinal section of wall at /:, showing of cells whose function is growtJi. These pu 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. Toronto : Macmillan
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbotany, bookyear1921
