202 Principles of Plant Culture. 



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, etc., normally 

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

 Plants that normally develop huds upon their roots, 

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

 propagated by cuttings. But propagation by cuttings 

 is not limited to such plants (362). 



360. The Essential Characteristics of a Cutting 

 are a — a certain amount of healthy tissue; b — a certain 

 amount of prepared food, or of tissue capable of pre- 

 paring food (58) ; c— in most species, a growing point 

 (66), either of the stem or root, or of both. 



361. The Farts 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 con- 

 tain one or more buds when practicable (127). 



362. Conditions that Favor the Growth of Cuttings, 

 a — A soil warmer than the air above it ("bottom 



heat") is important in growing many plants from cut- 

 tings. Warmth stimulates plant growth, and when ap- 

 plied 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 of roots is stimulated. Indeed 

 bottom heat often excites growth in cuttings that Avill 

 not grow without it. 



