. Elementary botany. Botany. IRRITABILITY. 129 were grown in a box, when thev were about 35CW high were .covered for nearly two da\s, so tliat the light was excluded. At midday on the second day the box was removed, and the leaves on the covered i^lants are well represented by fig. iig, which was made from one of them. The leaves of the other plants in the box which were not covered were horizontal, as shown by fig. 120. Now on leaving these plants, which had exhibited. Fig. 119. Sunflower plant. Epinastic con- dition of leaves induced during the day in darkness. on the upper side and the Fig
. Elementary botany. Botany. IRRITABILITY. 129 were grown in a box, when thev were about 35CW high were .covered for nearly two da\s, so tliat the light was excluded. At midday on the second day the box was removed, and the leaves on the covered i^lants are well represented by fig. iig, which was made from one of them. The leaves of the other plants in the box which were not covered were horizontal, as shown by fig. 120. Now on leaving these plants, which had exhibited. Fig. 119. Sunflower plant. Epinastic con- dition of leaves induced during the day in darkness. on the upper side and the Fig lao. Sunflower plant removed from darkness, leaves extending under mfluence of light (dialieliotro- pism.) induced "sleep" move- ments, exposed to the light they gradually assumed the horizontal position again. 265. lipinasty and hyponasty.—During the early stages of growth of many leaves, as in the sunflower plant, the direction of growth is different fnjm what it is at a later period. The under surface of the young leaves gro\^"s more rapidly in a longitudinal direction tlian the upper side, so that the leaves are held upward close against the bud at the end of the stem. This is termed hvpoiiasty, or the leaves are said to be hvponasiic. Later the growth is more rapid eaves turn d(.iwnward or away from the bud. This is termed epinasty, or the leaves are said to be epinastic. This is shown by the night position of the leaves, or in the induced "sleep " of the sun-. 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 Atkinson, George Francis, 1854-1918. New York : H. Holt
Size: 1459px × 1712px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisher, booksubjectbotany
