. Elements of botany. Botany; Botany. LEAVES. 91 120. Occurrence of Netted Veining and of Parallel Veining. — The student has already, in his experiments on germina- tion, had an opportunity to observe the difference in mode of veining betweep the leaves of some dicotyledonous plants and those of monoeotyledonous plants. This difference is general throughout these great groups of flowering plants. What is the difference ? The polycotyledonous pines, spruces, and other coniferous trees have leaves with but a single vein, or two or three parallel ones, but in their case the veining could hardly
. Elements of botany. Botany; Botany. LEAVES. 91 120. Occurrence of Netted Veining and of Parallel Veining. — The student has already, in his experiments on germina- tion, had an opportunity to observe the difference in mode of veining betweep the leaves of some dicotyledonous plants and those of monoeotyledonous plants. This difference is general throughout these great groups of flowering plants. What is the difference ? The polycotyledonous pines, spruces, and other coniferous trees have leaves with but a single vein, or two or three parallel ones, but in their case the veining could hardly be other than parallel, since the needle-like leaves are so narrow that no veins of any considerable length could exist except in a position lengthwise of the leaf. The fact that a certain plan of vena- tion is found mainly in plants with a particular mode of germination, of stem structure, and of arrangement of floral parts, is but one of the frequent cases in botany in which the structures of plants are correlated in a way which it is not easy to explain. No one knows why plants with two coty- ledons should have netted-veined leaves, but many such facts as this are familiar to every botanist. 121. Simple and Compound Leaves. — The leaves so far studied are simple leaves, that is, leaves of which the blades are more or less entirely united into one piece. But while in the elin the margin is cut in only a little way, in some maples it is deeply cut'^ in toward the bases of the veins. In some leaves the gaps between the adjacent portions extend all the way down to the petiole (in palmately veined leaves) or to. Fig. 74. — Parallel Veining in Canna. Veins running from midrib to 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 Bergen, Joseph Y. (Joseph Young), 1851-1917. Boston, Ginn
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1896
