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AGRONOMY 



plants, to which he adds various others which careful manip- 

 ulation and a knowledge of plant growth make possible. 

 Often injury to the plant will cause it to produce parts 

 designed for reproduction. Cuts near the base of bulbs or 

 corms will cause bulblets or cormels to develop. Even bulb 

 scales, when treated as softwood cuttings, may develop into 

 new plants. All vegetative multiplication depends upon a 

 division of the plant, which fact may be made use of in many 

 ways. Cormels and bulblets are removed from 

 the plant and treated like seeds. Rootstocks 

 are separated into bits, each of which contains 

 one or more buds and a few roots. Tubers, 

 like rootstocks, are cut into pieces, a single 

 specimen thus producing several new plants. 

 Runners, offsets, stolons, and suckers are sep- 

 arated from the parent plant and set where 

 wanted. Other species, such as the phlox, 



FIG. 134. A species of sunflower (Helianthus laetiflorus) showing the 

 evolution of a tuber from an offset 



golden glow, and chrysanthemum, which grow in clumps with- 

 out well-defined rootstocks or other means of propagation, 

 may be simply cut in pieces and each piece planted separately. 

 Chief among the artificial methods which man has devised 

 for multiplying plants may be named cuttings, layering, bud- 

 ding, and grafting. 



Cuttings. Nearly all plants may be increased in number by 

 detached parts, which, placed in moist sand or even water, 

 soon strike root and become independent individuals. The 

 " slips " by which house plants are commonly propagated are 



