. Botany; principles and problems. Botany. 164 BOTANY: PRINCIPLES AND PROBLEMS region of low content to one of higher. Such a response is known as an hydrotropism and results in the pursuit of moisture by roots for considerable distances, notably when the surface layers of the soil are drying out and the water table is descending. It is in responses of structural change rather than those of movement, however, that the effect of moisture is most often manifest. Plants which have access to abundant water supply. Fig. 81.—"Amphibious" plant. A shoot of mermaid weed (Proserjnnaca palustr
. Botany; principles and problems. Botany. 164 BOTANY: PRINCIPLES AND PROBLEMS region of low content to one of higher. Such a response is known as an hydrotropism and results in the pursuit of moisture by roots for considerable distances, notably when the surface layers of the soil are drying out and the water table is descending. It is in responses of structural change rather than those of movement, however, that the effect of moisture is most often manifest. Plants which have access to abundant water supply. Fig. 81.—"Amphibious" plant. A shoot of mermaid weed (Proserjnnaca palustris). Submersed leaves are finely divided, aerial leaves undivided, and leaves between, intermediate in form. grow luxuriantly, for the most part, with large leaves and rather soft tissues. Cuticle and epidermis are thin, woody tissues some- what weak, and parenchyma abundant. A similar plant grown where water is scanty becomes stunted throughout and has much smaller leaves. Its tissues, particularly the epidermis and cuticle, are much tougher, and the woody elements stronger and more abundant. In some instances even more profound structural changes are produced. The water buttercup, to cite a notable example, when growing on the shore produces normal buttercup leaves, but when submersed in water develops leaves which are dissected into fine capillary segments and are thus particularly well fitted for aquatic life. Other "amphibious" plants exhibit similar structural changes (Fig. 81).. 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 Sinnott, Edmund Ware, 1888-. New York, McGraw-Hill
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbotany, bookyear1923
