Propagation by Cuttings. 215 



roots will form at the base of the stem, and we shall 

 soon have a rooted cutting. Not all plants, however, 

 root freely in water, pcssibly owing to an insufficient 

 supply of oxygen therein. 



With very few exceptions, of which the greenhouse 

 smilax* is one, cuttings of the succulent growth of the 

 stem, with a certain amount of healthy leaf surface in- 

 tact, will develop roots in all plants, under proper con- 

 ditions of humidity and temperature ; hence propagation 

 from green cuttings is a very common and expeditious 

 method of multiplying plants. The healthy leaf sur- 

 face, capable of preparing food, is a very important 

 part of a green cutting, because the stem is less abun- 

 dantly supplied with reserve food during the growth 

 period than during the dormant period (184). 



Since the presence of leaf surface upon the cutting 

 greatly promotes transpiration (74), propagation from 

 green cuttings is scarcely practicable in the open air. 

 Bottom heat (362), with a comparatively low air tem- 

 perature, is especially important with green cuttings, in 

 order that the food prepared in the leaves may be de- 

 voted to the formation of roots. A small leaf surface 

 on the cutting is generally preferable to a larger one; 

 in many plants, a portion of a single leaf is sufficient. 

 The leaf surface should in no case be permitted to wilt, 

 hence the cuttings should generally be sprinkled with 

 water as soon as made. 



378. Especial Care is Necessary in Propagating 

 plants from Green Cuttings. In planting' the cuttings, 

 the material of the propagating bed should be put in 



* Asparagus meteloides. 



