. Plants; a text-book of botany. Botany. FOLIAGE LEAVES: THE LIGHT-RELATION. 23 stems against a support, as the ivies. It is only necessary to notice how the leaves are adjusted to light on an erect stem, ;aid then to bend the stum into a horizontal posi- tion or against a support, to realize how unfavorable the same arrangement would be. and how many new ad- justments must be made. The leaf blades must all be brought to the light side of the stem, so far as possible, and those that belong to the lower side of the stem must be fitted into the spaces left by the leaves which belong to the upper
. Plants; a text-book of botany. Botany. FOLIAGE LEAVES: THE LIGHT-RELATION. 23 stems against a support, as the ivies. It is only necessary to notice how the leaves are adjusted to light on an erect stem, ;aid then to bend the stum into a horizontal posi- tion or against a support, to realize how unfavorable the same arrangement would be. and how many new ad- justments must be made. The leaf blades must all be brought to the light side of the stem, so far as possible, and those that belong to the lower side of the stem must be fitted into the spaces left by the leaves which belong to the upper side. This may l)e brought about l\v the twisting of the stem, tlie twisting of the petioles, the bending of the blaile ou the petiole, the lengthening of j)etioles, or in some other way. Every horizontal stem has its own special problems of leaf adjustment which may be observed (see Figs. 18, 50). Sometimes there is not space enough for the full development of every blade, and smaller ones are fitted into the spaces left by the larger ones (see Fig. "21). This sometimes results in what are called unequally paired leaves, where opposite leaves develop one large blade and one small. Fig. 17. A chrj'santhemum, showing lobed leaves, the rising of the petioles to adjust the blades to light, and the general cylindrical 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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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1900
