THE PROPAGATION OF PLANTS 209 



food may be exhausted before the shoot reaches the 

 surface. When planted in the open ground (372), the 

 soil should be made very fine and carefully pressed about 

 the cuttings; if the weather is warm and dry, shading 

 (Fig. 64) and watering will be necessary. 



377. Propagation by cuttings from active plants (green 

 cuttings, slips) . — Nearly all plants may be propagated 

 from green cuttings. A succulent cutting of nasturtium 

 with its leaves intact, and with its proximal end im- 

 mersed in fresh well- or spring-water, will for a time 

 absorb sufficient of the liquid to make good the loss 

 from transpiration (74). So long as the water remains 

 fresh and the tissues of the stem are unobstructed, the 

 water thus absorbed will answer the same purpose to 

 this cutting as if it had been absorbed by the roots. Food 

 formation (58) will continue, and the growth current 

 (79) will transport the prepared food from the leaves 

 into the stem and in the direction of the roots. No roots 

 being present, however, the growing points of 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, possibly owing to the insufiicient supply of oxygen. 



With very few exceptions, of which the greenhouse 

 smilax (Asparagus asparagiodes) is one, cuttings of the 

 succulent growth of the stem, with a certain amount of 

 healthy leaf surface intact, will develop roots in all plants, 

 under proper conditions of humidity and temperature; 

 hence propagation from green cuttings is a very common 

 and expeditious method of multiplying plants. The 

 healthy leaf surface, capable of preparing food, is a very 

 important part of a green cutting, because the stem is 

 less abundantly supplied with reserve food during the 

 growth period than during the dormant period (184). 



