. Botany for agricultural students. Plants. Fig. 240. — A globular cactus, an example of a plant having leaves replaced by spines. After J. M. Coulter. Sometimes, as in the Corn, the rolling of the leaves decreases the surface exposed and lessens transpiration. {Fig. 2^1 •) The. Fig. 241. — Cross section of a Com leaf. I, lower epidermis; ;/, upper epidermis. Notice that the cells are larger on the upper side than on the lower side of the leaf. The cells of the upper epidermis, being larger, shrink more than those of the lower epidermis, and thus cause the rolling of the leaf in dry weather. M
. Botany for agricultural students. Plants. Fig. 240. — A globular cactus, an example of a plant having leaves replaced by spines. After J. M. Coulter. Sometimes, as in the Corn, the rolling of the leaves decreases the surface exposed and lessens transpiration. {Fig. 2^1 •) The. Fig. 241. — Cross section of a Com leaf. I, lower epidermis; ;/, upper epidermis. Notice that the cells are larger on the upper side than on the lower side of the leaf. The cells of the upper epidermis, being larger, shrink more than those of the lower epidermis, and thus cause the rolling of the leaf in dry weather. Much enlarged. leaves may have an edgewise position and thereby avoid the direct rays of the midday sun, as Wild Lettuce illustrates. The shedding of leaves from the plant is an important means of protection. Many of our trees shed some of their leaves during a. 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 Martin, John N. (John Nathan), b. 1875. New York, John Wiley ; London, Chapman & Hall
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectplants, bookyear1919
