. Science of plant life, a high school botany treating of the plant and its relation to the environment. Botany. Leaf Coloration and the Fall of Leaves 69 Self-pruning. A large number of our common trees, like the Cottonwood, maple, and elm, develop abscission layers which cut off twigs and some- times branches an inch ia thick- ness. In these trees we have twig faU as well as leaf faU. The falling of flowers, and of fruits like apples and nuts, is due to the abscission layers formed in the stems. Evergreen and deciduous trees. In the Northern states many persons have come to think that the ev
. Science of plant life, a high school botany treating of the plant and its relation to the environment. Botany. Leaf Coloration and the Fall of Leaves 69 Self-pruning. A large number of our common trees, like the Cottonwood, maple, and elm, develop abscission layers which cut off twigs and some- times branches an inch ia thick- ness. In these trees we have twig faU as well as leaf faU. The falling of flowers, and of fruits like apples and nuts, is due to the abscission layers formed in the stems. Evergreen and deciduous trees. In the Northern states many persons have come to think that the evergreen habit is associated only with needle leaves, because in the North the evergreens are ^, . ^, n 1 r 1 , ^i°- 43- Absdssion of branches mostly of the needle-leafed type, of cottonwood. Twigs and smaU But in the Southern states there branches as weU as leaves and fruits , , , r- J , T, are cut off by the fonnation of absds- are many broad-leafed trees, like ^^^^ ]3,yeTs. the magnoUa, rhododendron, and holly, that are also evergreen. Moreover, the tamaracks of the North and the bald C3^ress of the South furnish examples of needle-leafed trees that are deciduous. If we include the shrubs, there are many broad-leafed plants, both in the North and in the South, that have the evergreen habit. In the tropics most of the trees are evergreen, and almost aU have broad leaves. It must be noted that even in the case of evergreens individual leaves remain on the trees for only a limited number of years. The leaves of the evergreens are quite different structurally from the leaves of deciduous trees. The evergreens must be able to withstand freezing and thawing, and also the dry. 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 Transeau, Edgar Nelson, 1875-1960. Yonkers-on-Hudson, N. Y. , World Book Co.
Size: 1329px × 1880px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectbotany, bookyear1921
