. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. 70 VARIATIONS IN ROOT-STRUCTURE Wallflower diarch, and that of most Monocotyledons polyarch. A pith composed of parenchyma, which is sometimes thick- walled, is frequent in the roots of herbaceous Dicotyledons (Fig. 30) and in Monocotyledons (Fig. 29), but in woody Dicotyledons and Conifers the xylem-groups often meet at the centre. Roots also vary in the manner of thickening of the mature cells of the I'"iG, 2y.—Transverse section of the central part of the root of the Ins. C, cortex ; en.,
. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. 70 VARIATIONS IN ROOT-STRUCTURE Wallflower diarch, and that of most Monocotyledons polyarch. A pith composed of parenchyma, which is sometimes thick- walled, is frequent in the roots of herbaceous Dicotyledons (Fig. 30) and in Monocotyledons (Fig. 29), but in woody Dicotyledons and Conifers the xylem-groups often meet at the centre. Roots also vary in the manner of thickening of the mature cells of the I'"iG, 2y.—Transverse section of the central part of the root of the Ins. C, cortex ; en., endodermis ; , metaxylcm ; pa., passage cells ; pc, pericycle ; ph., phloem ; , protoxylem. A transverse section of the root of the Iris illustrates these features. It exhibits the typical Monocotyledonous structure, viz. a central pith and numerous alternating groups of xylem and phloem (Fig. 29). The endodermis [en) is conspicuous owing to the marked thickening of all but the outer walls of most of its cells. Opposite the protoxylem groups [), however, the cndodermal cells are often thin-walled, and [pa.). 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 Fritsch, Felix Eugene, 1879-; Salisbury, E. J. (Edward James), Sir, b. 1886. London, G. Bell and sons ltd.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectpl, booksubjectplants
