. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. GENERAL FEATURES OF SECONDARY THICKENING 119 The secondary wood thus added on the inside forms a larger and larger core each year (Fig, 58). Since it is composed of hard persistent tissue, there is practically no compression of the wood, which progressively accumulates, so that the increase in girth of the stem serves as a rough measure of the amount of tissue added. To this enlargement the secondary phloem con-. FiG. 58.—Diagram showing the arrangement of tissues in a transverse section of a woody trunk abou
. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. GENERAL FEATURES OF SECONDARY THICKENING 119 The secondary wood thus added on the inside forms a larger and larger core each year (Fig, 58). Since it is composed of hard persistent tissue, there is practically no compression of the wood, which progressively accumulates, so that the increase in girth of the stem serves as a rough measure of the amount of tissue added. To this enlargement the secondary phloem con-. FiG. 58.—Diagram showing the arrangement of tissues in a transverse section of a woody trunk about tAventy-four years old. The large vessels of the spring wood of each annual ring are shown as black dots. b., bark ; c, of cambium ; p., pith ; Ph., secondary phloem ; pr., primary ray ; Sy., secondary ray. tributes but little, since this tissue is mainly thin-walled, and the outer earlier-formed elements become compressed more and more, as a consequence of the increasing pressure resulting from the growth of the wood and the annual formation of intercalated phloem. The cambium keeps pace with the enlargement of the circumference of the secondary wood by tangential stretching and occasional radial divisions in its cells. The pressure on the outer tissues, due to the interpolation. 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
