THE PROPAGATION OF PLANTS 191 



couraged by covering the brahch with soil. When well 

 rooted, the young plants may be separated from the 

 parent by cutting the stolons. 



Woody plants grown from stolons are seldom uniform 

 in size and are not often so well rooted as those grown 

 from cuttings (358). Some herbaceous plants are, how- 

 ever, more readily propagated by stolons than by any 

 other means. 



The offset by which the houseleek (Sempervivum) 

 is so readily propa- 

 gated, is a very short 

 stolon that forms a 

 single tuft of leaves 

 at its apex. The cane 

 of the black cap rasp- 

 berry (Rubus occiden- 

 tal-is) , which roots from 



the tip (Fig. 85), and ^"'- ^^- " ^^""'^^ °^ ^^'^ strawberry. 



the runner of the strawberry (Fig. 86), that forms 

 a plant at each alternate node, are modified stolons. 



348. Propagation by layers or layering. — The layer is 

 an artificial stolon, i.e., a branch that does not naturally 

 grow downward, which is covered with or surrounded 

 by moist soil or other media to stimulate the production 

 of roots (88). The branch may be bent down and cov- 

 ered, as is usually practiced with the grape, wisteria, 

 etc., or the soil may be ridged up about the branch, as 

 is done with the quince and paradise apple. In either 

 case the terminal portion of the stem is commonly left 

 uncovered. In the latter method, which is known as 

 mound-layering (Fig. 87), the stems of the plant to be 

 layered are usually cut off just above the surface of the 

 ground in early spring, to stimulate the formation of 



