. Botany for high schools. Botany. 88 GROWTH AND WORK OF PLANTS leaf, so that the water is conserved. These leaves often closely overlap or lie close against the stem as scales. The cassiope (Cassiope tetragona)^ which is found in sphagnum moors in some of the Northern States, and is common from Labrador to Green- land and Alaska, is an example. 149. Needle-like leaves.—These are found on many coni- fers, especially the pines. The leaves are long, narrow, and thick, and are called needle leaves. They have a thick, waxy cuticle, an epidermis with thick walls. Beneath the epidermis there are sev
. Botany for high schools. Botany. 88 GROWTH AND WORK OF PLANTS leaf, so that the water is conserved. These leaves often closely overlap or lie close against the stem as scales. The cassiope (Cassiope tetragona)^ which is found in sphagnum moors in some of the Northern States, and is common from Labrador to Green- land and Alaska, is an example. 149. Needle-like leaves.—These are found on many coni- fers, especially the pines. The leaves are long, narrow, and thick, and are called needle leaves. They have a thick, waxy cuticle, an epidermis with thick walls. Beneath the epidermis there are several layers of cells the walls of which are very thick and hard, and inside is the mesophyll. This form and structure of the pine leaves enables them to conserve water so that they lose it very slowly; otherwise the leaves would lose so much water that in winter the trees would be killed. The spruces have similar leaves, but they are shorter and more flattened, while some other evergreens have scale leaves, which with their structure enables them to endure the drying effect of the cold winters. 150. Modifications of leaves combining the normal func- tions with other utilities. — First, tendrils and tendrils on leaves, as in the pea; also where the petiole of the leaf functions as a tendril, as in the vir- gin's bower {Clematis). Second, the leaves of insectivorous plants, like the Venus's flytrap, the sundew (see paragraph 138), and the pitcher plants, of which a good example is the com- mon pitcher plant of our sphagnum moors. Here the leaf is modified into a pitcher- shaped structure, broadened near the middle and narrowed somewhat near the free end, where there are on the inside of the pitcher numerous bristle-like hairs pointing Fig. 78. Tendrils of sweet pea coiling around 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
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