. Textbook of botany. Botany. ROOTS AND THEIR USES 171 bark; but the bark of roots does not grow so fast nor be- come so thick as that of stems often does. 193. Occurrence of Adventive Roots. — Not a few plants, like the Indian com, produce adventive roots regularly and in considerable numbers. A potato shoot growing from an eye of a tuber sends out adventive roots from its lower part. Plants with long underground stems, hke the may-apple, as well as many trailing plants, pro- duce adventive roots from time to time. As the older parts of such a plant, in- cluding its primary root, die, its roo
. Textbook of botany. Botany. ROOTS AND THEIR USES 171 bark; but the bark of roots does not grow so fast nor be- come so thick as that of stems often does. 193. Occurrence of Adventive Roots. — Not a few plants, like the Indian com, produce adventive roots regularly and in considerable numbers. A potato shoot growing from an eye of a tuber sends out adventive roots from its lower part. Plants with long underground stems, hke the may-apple, as well as many trailing plants, pro- duce adventive roots from time to time. As the older parts of such a plant, in- cluding its primary root, die, its root system comes to consist entirely of adven- tive roots. Some climbing plants form adventive roots in large numbers ; but such plants usually remain con- nected with the soil by means of a primary root, and the adventive roots are useful chiefly to assist the plants in climbing. Many plants form adventive roots in response to the stimulus of a wound. In some kinds of trees, for example, girdhng (see § 232) is followed at first by the formation of adventive roots on the upper edge of the wound, and in other kinds it is followed by the formation of adventive buds (which may develop into branches) on the lower edge of the wound. If a leaf of a rex begonia is cut into several pieces and these are stuck. Fig. 106. —,A leaf of Bryophyllitm which is producing new plants — a case of vegetative multiplication. This leaf was placed on moist sand, and in a few days adventive buds and adventive roots developed wherever the veins extended to the edges of the 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 Allen, Charles E. (Charles Elmer), b. 1872; Gilbert, Edward Martinius, joint author. Boston, New York [etc. ] D. C. Heath & co
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