. Plant life [microform]. Botany; Botanique. HOW PLANTS BAT. 47 tho edge IS not quito liUod out, but irrocularlv mdented, we get forum like the oak leaf, iinally, when tho uulentations go to the very bottom of each vein, so as to reach the midrib we get a compound loaf hke that of the vetch' wiUi a number of opposite and distinct leaflets. ' The reason why some leaves are thus more hlled out than others is simply this: it depends upon .he freedom of their access to air and sunlight. I do not mean the freedom of access of the particular leaf or tho particular plant, but tho average ancestral fr
. Plant life [microform]. Botany; Botanique. HOW PLANTS BAT. 47 tho edge IS not quito liUod out, but irrocularlv mdented, we get forum like the oak leaf, iinally, when tho uulentations go to the very bottom of each vein, so as to reach the midrib we get a compound loaf hke that of the vetch' wiUi a number of opposite and distinct leaflets. ' The reason why some leaves are thus more hlled out than others is simply this: it depends upon .he freedom of their access to air and sunlight. I do not mean the freedom of access of the particular leaf or tho particular plant, but tho average ancestral free- dom of access in the kind they belong to. Each kind has adapted itself, as a rule, to certain situa- tions for \\,iich it has special advantages, and it has learnt by the teach- ing of natural selection to produce such leaver as best fit its chosen site and habits. Where access to carbon and sunlight IS easy, plants usually produce very full round leaves, with all the interstices between the ribs tilled amply in with cellular tissue; but where access is difficult, they usually produce ra%er starved and unfilled leaves, which consist, as it Z^^%u- f^^^^^y covered skeletons (Figs. 4 and pj. ihis last condition is particularly observable in submerged leaves, and in those which grow m very crowded liQ. 6.—I. Parallel veins, as seen in one great group of plants, the lilies. II. Branching veins, as seen in another great group, the trees and herbs of the usual 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 Allen, Grant, 1848-1899. London : Hodder and Stoughton
Size: 1797px × 1391px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookau, bookpublisherlondonhodderandstoughton, booksubjectbotany
