. Introduction to structural and systematic botany, and vegetable physiology. Botany. 156 THE LEAVES. 241) ; if two such ribs proceed from each side of the midrib, it is said to be quintuple-ribbed, or 279. Not unfrequently the vessels of a reticulated leaf divide at the apex of the petiole into three or more portions or ribs of nearly equal size, which are usually divergent, each giving off veins and veinlets, like the single rib of a feather-veined leaf. Such leaves are termed radiated-veined, or palmately-veined; and, as to the number of the ribs, are called three-ribbed,
. Introduction to structural and systematic botany, and vegetable physiology. Botany. 156 THE LEAVES. 241) ; if two such ribs proceed from each side of the midrib, it is said to be quintuple-ribbed, or 279. Not unfrequently the vessels of a reticulated leaf divide at the apex of the petiole into three or more portions or ribs of nearly equal size, which are usually divergent, each giving off veins and veinlets, like the single rib of a feather-veined leaf. Such leaves are termed radiated-veined, or palmately-veined; and, as to the number of the ribs, are called three-ribbed, five-ribbed, seven-ribbed, &c. (Fig. 244, 247, 253). Examples of this form are furnished by the Maple, the Gooseberry, the Mallow family, &c. Occasionally the ribs of a radiated-veined leaf converge and run to the apex of the blade, as in Rhexia and other plants of the same family, thus resem- bling a parallel-veined or nerved leaf; from which, however, it is distinguished by the intennediate netted veins. But when the ribs are not very strong, such leaves are frequently said to be nerved, although they branch before reaching the apex. 280. According to the theory of De Candolle (275), the shape which leaves assume may be viewed as dependent upon the dis- tribution of the veins, and the quantity of parenchyma; the gen- eral outline being determined by the division and direction of the veins ; and the form of the margin, (whether even and continuous, or else interrupted by void spaces or indentations,) by the greater or FIG. 231-244. Various forms of simple 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 Gray, Asa, 1810-1888. New York [etc. ] Ivison, Blakeman, Taylor & Co.
Size: 1701px × 1469px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorgra, bookcentury1800, bookdecade1850, booksubjectbotany
