. Botany for agricultural students . Botany. ABSORBING TISSUES 131 well as conductive tissue. {Fig. 118.) In Flowering Plants, although tracheids are present, the water-conducting tissue is composed mainly of cells which fit together end to end and thus form a continuous series. The end walls of the cells of the series are resorbed and thus are formed continuous tubes, called ducts, vessels, or tracheae, the last name referring to their resem- blance to the human trachea. In the phloem, the main conductive tissue is composed of the sieve tvibes, which are so named because of the perforations i
. Botany for agricultural students . Botany. ABSORBING TISSUES 131 well as conductive tissue. {Fig. 118.) In Flowering Plants, although tracheids are present, the water-conducting tissue is composed mainly of cells which fit together end to end and thus form a continuous series. The end walls of the cells of the series are resorbed and thus are formed continuous tubes, called ducts, vessels, or tracheae, the last name referring to their resem- blance to the human trachea. In the phloem, the main conductive tissue is composed of the sieve tvibes, which are so named because of the perforations in their waUs. Unlike tracheae, which have thickened woody areas in their walls, sieve tubes have thin cellulose walls and retain their protoplasm. With the sieve tubes usually occur thin-waUed elongated cells, known as companion cells, and parenchyma cells, both of which aid in conduction. Absorbing Tissues. — In the higher plants, where the plant body is dif- ferentiated into roots, stem, and leaves, the roots are especially devoted to absorption. In case of soil roots, the root Fig. 118. — Tracheids from wood of Pine, showing the tapering ends and the bor- dered pits (p). After Cham- 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 Martin, John N. (John Nathan), b. 1875. New York : John Wiley & Sons, Inc.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
