. The power of movement in plants . Plants; Botany. Chav. Vll. SLEEP OF LEAVES. 391 leuves rise so much at night that they may almost be said to sleep. Strepkium floribundum' (Grnminese) — The oval leaves are provided with a pulvinus, and are extended horizontally or declined a little beneath the horizun during the day. Those on the upright culms simply rise up vertically at night, so their tips are directed towards the zenith. (Fig. IfrL) Fig. Strephium fioribundum: culms with leaves during the iny, and wheQ aslfe|.' at night. Figures reduced. Horizontally extended leaves arising
. The power of movement in plants . Plants; Botany. Chav. Vll. SLEEP OF LEAVES. 391 leuves rise so much at night that they may almost be said to sleep. Strepkium floribundum' (Grnminese) — The oval leaves are provided with a pulvinus, and are extended horizontally or declined a little beneath the horizun during the day. Those on the upright culms simply rise up vertically at night, so their tips are directed towards the zenith. (Fig. IfrL) Fig. Strephium fioribundum: culms with leaves during the iny, and wheQ aslfe|.' at night. Figures reduced. Horizontally extended leaves arising from much inclined or almost horizontal culms, move at night so that their tips point towards the apex of the culm, with one lateral maraiii directed towards the zenith; and in order to assume this position the leaves have to twist on their own axes through an angle of nearly 90°. Thus the surface of the blade always stands vertically, whatever may be the position of the midrib or of the leaf as a whole. The circumnutation of a young leaf (2 • 3 inches in length) was traced during 48 h. (Fig. 165). The movement was remarkably simple; the leaf descended from before until 2 or , and then rose so as to stand vertically at about 6 , descending again late in the night or in the very early morning. * A. Brongiiiart first observed la Soc. Bot. de France,* torn, vii that the leaves of this plan t and X860, p. 470. of Miirsilua sleep: see ' Bull, de 26. 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 Darwin, Charles, 1809-1882; Darwin, Francis, Sir, 1848-1925. New York : D. Appleton
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Keywords: ., bookcentury1800, bookdecade, booksubjectbotany, booksubjectplants
