. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. STEM-STRUCTURE 339 tains schizogcnous rcsin-canals (r.), whose structure has ah'eady been described (cf. p. 152). These resin-canals are particularly characteristic of Conifers, and are found in all parts of the plant ; the}' are entirely absent only from the Yew. The primary and secondary vascular tissues are not easily distinguished from one another, particularly in the case of the phloem, the broad zone of which is chiefly secondary in Fig. 196.—Structure of the young stem of the Scotch Fir (Pinus
. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. STEM-STRUCTURE 339 tains schizogcnous rcsin-canals (r.), whose structure has ah'eady been described (cf. p. 152). These resin-canals are particularly characteristic of Conifers, and are found in all parts of the plant ; the}' are entirely absent only from the Yew. The primary and secondary vascular tissues are not easily distinguished from one another, particularly in the case of the phloem, the broad zone of which is chiefly secondary in Fig. 196.—Structure of the young stem of the Scotch Fir (Pinus sylvestris) in transverse section. A, Entire section (diagrammatic). B, Small part of the pcriplieral tissues enlarged. C, Single resin-canal enlarged, showing the epithelium (op.). Ca., cork cambium ; e., epidermis ; Ph., phloem ; r., resin-canals ; Xy., xylcm. This tissue (Ph.) is strikingly uniform, its elements, which have thick white shining walls, exhibiting a radial arrangement. The rows of more or less empty-looking sieve-tubes, which have no companion cells, are interspersed with a smaller number of irregular files of phloem-parenchjina, whose cells contain dense contents. In longitudinal sections the sieve-tubes appear as long tapering elements bearing sieve-areas (Fig. 197, E, si.) upon their sloping radial walls. The secondary wood (Fig. 196, Xy.), internal to the narrow. 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
