188 Principles of Plant Culture. 



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 

 considered here. It consists in taking up the plant, pre- 

 ferably 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). 



B PROPAGATION BY DETACHED PARTS. 



This comprises two different modes of propagation, 

 viz. , by specialized buds and by sections of the plant. 



a~ Propagation by Specialized Buds. 



351. This includes propagation by bulbs, bulblets, corms 

 and tubers. It is in a sense intermediate between prop- 

 agation by parts intact (346) and by cuttings (358). The 

 bud that is to form the future plant, though not having 

 roots of its own, has been specially prepared by the 

 parent, through an abundant food supply and a partially 

 dormant condition of the protoplasm, to maintain a sep- 

 arate existence, even under adverse conditions, and in 

 due time to develop into a plant. In these respects it 

 resembles the seed, from which it differs, however, in the 

 less dormant condition of its protoplasm and in not being 

 the product of sexual fecundation (341). 



