. The power of movement in plants . Plants; Botany. Chap. Vll. SLEEP OF LEAVES. 391 leaves rise so much at night that they may almost be said to Strephium floribundum* (Graminese). — The oval leaves aro provided with a pulvinus, and are extended horizontally or declined a little beneath the horizon during the day. Those on the upright culms simply rise up vertically at night, so that their tips are directed towards the zenith. (Kg. 164.) Fig. Strephium floribuiutum: culms with leaves dining tlie day, and when asleep at night. Figures reduced. Horizontally extended leaves arising from muc
. The power of movement in plants . Plants; Botany. Chap. Vll. SLEEP OF LEAVES. 391 leaves rise so much at night that they may almost be said to Strephium floribundum* (Graminese). — The oval leaves aro provided with a pulvinus, and are extended horizontally or declined a little beneath the horizon during the day. Those on the upright culms simply rise up vertically at night, so that their tips are directed towards the zenith. (Kg. 164.) Fig. Strephium floribuiutum: culms with leaves dining tlie day, and when asleep 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 margin directed towards the zenith; and in order to assume this position the leaves have to twist on their ovm 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 oiroumnutation of a young leaf (2'3 inches in length) was traced during 48 h. (Pig. 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. Brongoiart first observed la Soc. Bot. de France,' torn, vii that the leaves of this plant and 1860, p. 470. of Marsilea sleep.: see ' Bull, de. 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, booksubjectbotany, booksubjectplants, bookyear18
