Propagation by Parts [ntact. 181 
Many woody plants that do not readily form roots when 
layered, may be induced to do so by mutilating the stem 
somewhat in the 
covered part. This 
tends to restrict 
the growth current 
(80) and causes an 
accumulation of 
reserve food, from 
which roots may 
originate. Gird- 
ling, twisting, 
bending or splitting 
the stem for a short 
Fic. 84. Layered branch of currant, split to encour- 
distance will often age the formation of roots. 
have the desired effect (Fig. 84). 
Layering is a very reliable and expeditious method of 
propagating many woody and herbaceous plants. 
350. Propagation by Division of the Crown of the 
plant, which is practicable with many perennial herbs, as 
the rhubarb, dahlia, globe artichoke etc., though not strictly 
analogous to propagation by stolons or layers, may be con- 
sidered here. It consists in taking up the plant, preferably 
while dormant, and cutting the crown into two or more 
parts, according to its size or the number of plants desired, 
and planting the divisions as separate plants. This method 
is applicable to propagation for private use, rather than for 
sale purposes. 
Propagation by approach grafting, although in order here, 
is more readily treated with the other methods of grafting 
(399). 
