. Botany of the living plant. Botany; Plants. GROWTH, IRRITABILITY AND MOVEMENT 165. Pig. 100. Leaf of Dionaea in the receptive state. (After Darwin.) ( x 4.) from glandular hairs on the upper surface. The movements of the Venus Fly Trap [Dionaea), an American plant, are very strik- ing. Each of the rosette of leaves of the plant bears at its distal end a two-flapped mechanism, like the covers of a book, mobile along the median line as a hinge (Fig. 100). The flaps are furnished with marginal spines, while three sensitive bristles rise erect from the upper surface of each. Under favourable con
. Botany of the living plant. Botany; Plants. GROWTH, IRRITABILITY AND MOVEMENT 165. Pig. 100. Leaf of Dionaea in the receptive state. (After Darwin.) ( x 4.) from glandular hairs on the upper surface. The movements of the Venus Fly Trap [Dionaea), an American plant, are very strik- ing. Each of the rosette of leaves of the plant bears at its distal end a two-flapped mechanism, like the covers of a book, mobile along the median line as a hinge (Fig. 100). The flaps are furnished with marginal spines, while three sensitive bristles rise erect from the upper surface of each. Under favourable condi- tions, a touch on any of these six bristles results in the immediate closure of the flaps, with interlock- ing of the marginal spines. Any insect touching them would be cap- tured within the trap ; and as the inner leaf-surfaces are furnished with secret- ing glands, digestion follows, with the usual absorption of the soluble products of digestion. The movement is due to combined turgor and growth changes. 5. Hygroscopic Movements. All the instances of movement in plants that we have so far considered, whether tropic or nastic, depend en changes of growth or turgor, and therefore involve living cells. There is, however, another class of movements in plants which stand in no direct relation to living cells, and which are physical rather than physiological in nature. These move- ments can take place in dead plant organs and are due to changes in water content of the tissues, in combination with special struc- tural features. Such hygroscopic movements are seen in the dehiscence of many fruits, and. 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 Bower, F. O. (Frederick Orpen), 1855-1948; Wardlaw, C. W. (Claude Wilson), 1901-. London, Macmillan and Co. , ltd.
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