. Botany for agricultural students. Plants. 130 CELLS AND TLSSUES only much thifkened l)ut also made woody â a feature in which they differ from collenchyma and bast fibers, where the thicken- ings are mainly of cellulose. {Fig. 116.) Where the wood fibers are abundant, as in Oaks, the wood is compact. Likewise, due to a greater numl^er of wood fibers, fall wood is more compact than spring Fig. 116. âa wood fiber, con- sisting of a much elongated cell with thick woody walls. Fig. 117. â Very much enlarged lengthwise section through an Alfalfa stem, showing the conductive and food- makin
. Botany for agricultural students. Plants. 130 CELLS AND TLSSUES only much thifkened l)ut also made woody â a feature in which they differ from collenchyma and bast fibers, where the thicken- ings are mainly of cellulose. {Fig. 116.) Where the wood fibers are abundant, as in Oaks, the wood is compact. Likewise, due to a greater numl^er of wood fibers, fall wood is more compact than spring Fig. 116. âa wood fiber, con- sisting of a much elongated cell with thick woody walls. Fig. 117. â Very much enlarged lengthwise section through an Alfalfa stem, showing the conductive and food- making tissues of the stem. /, tracheae (commonly called xylem), which constitute the water-conducting tissue; â p, the conductive tissue (commonly called phloem), which conducts the food made by the leaves; c, the food-making and storage tissue (cortex) just under the epidermis (e). The cells of the cortex contain chloroplasts {ch). a, cambium. Conductive Tissues. â The conductive tissues of plants are of two kinds, xylem and phloem, which occurring together form the vascular bundles through which water, mineral salts, and foods are distributed to all parts of the plant. {Fig. 117.) The xylem is devoted chiefly to carrying water with what it may have in solution and the phloem to carrying foods. Furthermore, the xylem and phloem differ in that the conductive cells of the former are empty while the conductive cells of the latter retain their pro- toplasm. In Conifers, such as Pines, Firs, etc., the water-conduct- ing cells have tapering ends and do not form a continuous series. They have peculiar pits in their walls, known as bordered pits, through which the liquids pass from cell to cell. They are com- monly known as tracheids, meaning "; Other plants have tracheids, but tracheids with bordered pits are characteristic of Conifers. The tracheids are also important strengthening as. Please note that these images are extracted from scanned page images that
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectplants, bookyear1919
