. Elementary biology; an introduction to the science of life. Biology. 48 ELEMENTARY BIOLOGY years, and to give protection to other kinds of plants until the earth has become compact (Fig. 12). Although roots do not generally put forth buds or shoots, the roots of some shrubs and trees â as certain willows, poplars, and hawthorns â do so, and can be used for propa- gating the species. In some plants the roots will form new shoots if the old shoot is completely removed or destroyed. On the other hand, roots frequently arise from stems or leaves, thus making pos- sible the propagation of plants
. Elementary biology; an introduction to the science of life. Biology. 48 ELEMENTARY BIOLOGY years, and to give protection to other kinds of plants until the earth has become compact (Fig. 12). Although roots do not generally put forth buds or shoots, the roots of some shrubs and trees â as certain willows, poplars, and hawthorns â do so, and can be used for propa- gating the species. In some plants the roots will form new shoots if the old shoot is completely removed or destroyed. On the other hand, roots frequently arise from stems or leaves, thus making pos- sible the propagation of plants by means of cuttings. Roots that originate in this manner are called adventi- tious roots. Most of our common house plants, and willows and other trees, can be propagated by keeping twigs in water or wet sand until roots appear, and then transplanting them into soil. If the leaf (or even a piece of leaf) of a begonia or of a bryophyllum be placed on damp earth or sand, tiny roots will be seen growing from various points along the edge in the course of a few days. In these species buds will also be produced, so that after a while we can separate small but complete plants from the leaf, and get these to grow into full-sized individuals (Fig. 13). Blackberry and raspberry bushes are frequently propagated by layering, which consists in bending the flexible stems out and burying the tips in the ground. Adventitious roots are formed on the covered portions, and, later, buds form new shoots. The old connecting stem is then cut away. A similar. â .'.â¢â¢;>;.vAiV«iV. Fig. 15. Climbing roots The English ivy, like many other climbing plants, clings to its support by means of adven- titious roots that grow out all along the stem. 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 Gruenberg, Benjamin C. (Benjam
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