THE PROPAGATION OF PLANTS 197 



of plants to develop from cuttings. In certain loca- 

 tions in southern Europe and in parts of South Amer- 

 ica, branches of the common apple tree, sharpened and 

 driven into the ground as stakes, often take root and 

 sometimes even bear fruit during the same season. A 

 warm, moist atmosphere is very favorable to propaga- 

 tion by cuttings. 



We have seen that the roots of certain plants nor- 

 mally develop buds (130). In like manner, the stems of 

 many plants, as the potato, grape and the like, normally 

 develop growing points of roots at their nodes (115). 

 Plants that normally develop buds upon their roots, 

 or growing-points of roots at their nodes, are readily 

 propagated by cuttings. But propagation by cuttings 

 is not hmited to such plants (362). 



360. Characteristics of a cutting. — The essential 

 characteristics of a cutting are : a certain amount of 

 healthy tissue ; a certain amount of prepared food, or 

 of tissue capable of preparing food (58) ; in most species, 

 a growing point (66), or the power of developing one. 



361. Parts used for cuttings. — The parts of plants to 

 be used for cuttings, therefore, are preferably the younger, 

 matured growths, since the tissues of these are most 

 vigorous; or else a part that possesses a certain amount 

 of healthy and vigorous leaf tissue. The cutting should 

 always contain one or more buds when practicable (127). 



362. Conditions that favor the growth of cuttings. — 

 A soil warmer than the air above it (" bottom heat ") 

 is important in growing many plants from cuttings. 

 Warmth stimulates plant growth, and when applied to 

 one part of a plant, it stimulates growth in that part. If the 

 soil about a planted cutting is warmed to a temperature 

 considerably higher than that of the air above, the growth 



