. Class-book of botany : being outlines of the structure, physiology, and classification of plants ; with a flora of the United States and Canada . Botany; Botany; Botany. OF THK VEINS. 53 apex, as seen in the leaf of the oak or birch. If there be several simi- lar divisions of the petiole, radiating from the base of the leaf, they are appropriately termed veins ; and the leaf is said to be three-veined, five-veined, etc. Jix. maple. 257. The primary branches sent off from the midvein, or the veins we may term the veinlets, and the secondary branches, or those sent off from the veinlets, are t
. Class-book of botany : being outlines of the structure, physiology, and classification of plants ; with a flora of the United States and Canada . Botany; Botany; Botany. OF THK VEINS. 53 apex, as seen in the leaf of the oak or birch. If there be several simi- lar divisions of the petiole, radiating from the base of the leaf, they are appropriately termed veins ; and the leaf is said to be three-veined, five-veined, etc. Jix. maple. 257. The primary branches sent off from the midvein, or the veins we may term the veinlets, and the secondary branches, or those sent off from the veinlets, are the veinulets. These also branch and subdi- vide until they become too small for loa 109 Tarieties of venation. 106, feather-veined,—ieaf of Betulapopulifolia (wliitc birch), lying upon a leaf of plum-tree; same venation ^vith different outlines. 107, Palmate-veinerl.—leaf of white maple, contrasted with leaf of Circis Canadensis. 108, Parallel venation,—plant of " three-leaved Solomon's-seal," (Asteranthemum trifoUatum .ffiijiiA.) 109, Forked venation,—climbing fern (Lygodium). 258. Modes op venation. Botanists distinguish three principa. modes of venation, which are in general characteristic of the three grand divisions of the vegetable kingdom already noticed. Reticulate, ob net-veined, as in the Exogens : this kind of vena- tion is characterized by the frequent reunion or inosculation of its nu- merously branching veins, so as to form a kind of irregular net-work. Parallel-veined, as in the Endogens. The veins, whether straight or curved, run parallel, or side by side, to the apex of the leaf, or to the margin, and are always connected by simple transverse veinlets. Fork-veined, as in the ferns (and other Cryptogamia, where veins are present at all). Here the veins divide and subdivide in a furcats manner, and do not Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability
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