. Plant life and plant uses; an elementary textbook, a foundation for the study of agriculture, domestic science or college botany. Botany. 8o THE PLANT: A GENERAL INTERNAL VIEW Another tissue of the stele is the phloem. (See Figures 2g and jo.) Through the phloem the naanufactured food principally moves, having descended from the leaves. The advantage to roots in having the harder tissues in the center rather than on the outside is evident. Think of the way they must bend and burrow in the soil. But. Fig. 29. ââ Cross section of a young root showing root-hairs. The outermost layer of cells is
. Plant life and plant uses; an elementary textbook, a foundation for the study of agriculture, domestic science or college botany. Botany. 8o THE PLANT: A GENERAL INTERNAL VIEW Another tissue of the stele is the phloem. (See Figures 2g and jo.) Through the phloem the naanufactured food principally moves, having descended from the leaves. The advantage to roots in having the harder tissues in the center rather than on the outside is evident. Think of the way they must bend and burrow in the soil. But. Fig. 29. ââ Cross section of a young root showing root-hairs. The outermost layer of cells is the epidermis. Note that the root-hairs are really prolongations out- wards of certain cells of the epidermis. The thin-walled tissue of larger cells is the cortex. The central region of smaller cells is the stele. The thick-waMed cells are xylem. The cells with shaded contents are phlo'im. with the stem it is different. In it the tissues of the stele are differently arranged. Here rigidity is an advantage. The leaves must be held firmly up in the light. The stem must have strength to withstand winds. The phability of the root would be a disadvantage to the stem, unless it is the stem of a creeping or climbing plant. Evidently it is an advantage to most stems to have the tissue-arrange- ment of the root reversed; it is better to have the stronger. 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 Coulter, John G. (John Gaylord), b. 1876. New York, American Book Co
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1913
