. Plants; a text-book of botany. Botany. 234 PLANT STEUCTUEES. Fig. 216. SLttion across a young twig of tiox elder, showing the foQr stem regions: e, epidermis, represented by the heavy boimding line; c, cortex; w, vascular cyl- inder; 75, pith.âFrom "Plant Relations.'^ eter of woody stems (Fig. 217, iv), and a possible increase of the branch system and foliage dis- play each year. (3) Leaf veins form- ing an open system (Fig. 216, figure to right). The network of smaller veinlets between the larger veins is usually very evident, especially on the under surface of the leaf, suggesting the
. Plants; a text-book of botany. Botany. 234 PLANT STEUCTUEES. Fig. 216. SLttion across a young twig of tiox elder, showing the foQr stem regions: e, epidermis, represented by the heavy boimding line; c, cortex; w, vascular cyl- inder; 75, pith.âFrom "Plant Relations.'^ eter of woody stems (Fig. 217, iv), and a possible increase of the branch system and foliage dis- play each year. (3) Leaf veins form- ing an open system (Fig. 216, figure to right). The network of smaller veinlets between the larger veins is usually very evident, especially on the under surface of the leaf, suggesting the name "net-veined" leaves, in contrast to the " parallel-veined " leaves of Mono- cotyledons. The vein system ends freely in the margin of the leaf, forming an '⢠open ; In consequence of this, although the leaf may remain entire, it very commonly be- comes toothed, lobed, and divided in various ways. Two main types of venation may be noted, which influence the form of leaves. In one case a single very prominent vein (riV) runs through the mid- dle of the blade, and is called the midrib. Fig. 2IT. section across a twig of box elder T? +I1 â 11 +1» * threi' ye:irs old, showing three annual rings, ±lr0m tills all tne mi- or growth rings, in the vascular cylinder; the nor veins arise as radiating lines (m) which cross the vascular hrn-nnViPs (V\a<i 918 region (w) represent the pith rays, the princi- orauoues (,-Cigb. ^J-O, pal ones extending from the pith to the cor- 219), and such a leaf tex (c).âFrom " Plant ;. 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 Coulter, John Merle, 1851-1928. New York, D. Appleton and company
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