. Introduction to botany. Botany. CHAPTER VI SPECIAL FUNCTIONS AND FORMS OF STEMS 82. Stems not always for the support of leaves. In Chap- ter "\^ considerable space was given to explanations of some of the ways in which stems serve to support leaves in advan- tageous positions for photosynthetic work. This is not, how- ever, by any means the only function of the stem or portions of the stem. Something was said in Chapter IV about the importance of food storage in stems, and something in section 56 about their work of photosynthesis. Some other important things done by whole stems, or by
. Introduction to botany. Botany. CHAPTER VI SPECIAL FUNCTIONS AND FORMS OF STEMS 82. Stems not always for the support of leaves. In Chap- ter "\^ considerable space was given to explanations of some of the ways in which stems serve to support leaves in advan- tageous positions for photosynthetic work. This is not, how- ever, by any means the only function of the stem or portions of the stem. Something was said in Chapter IV about the importance of food storage in stems, and something in section 56 about their work of photosynthesis. Some other important things done by whole stems, or by more or less highly specialized portions of them, will be discussed m the present chapter. 83. Storage of air or water in the stem. It sel- dom happens that the same plant would be benefited by storing both air and -neater abundantly in its roots or stems ; but marsh and water plants may evidently be much aided in their respiration by holding a good deal of air inside the plant body. In some such plants the air passages and air cavities form a complex system, ^vhich extends all the way from the stomata to the tips of the roots. A section across the stem of any of the common pondweeds (^Potamogeton) (fig. 68) shows clearly how large and abundant its air passages are. 85. Fig. 68. Cross section of stem of pond- weed {Poiamogeton), showing air passages a, much magnified. After Green. 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 Bergen, Joseph Y. (Joseph Young), 1851-1917; Caldwell, Otis William, 1869- joint author. Boston, New York, [etc. ] Ginn and company
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