PROPAGATION BY NODES 



25 



the fl()\v(>r, certain iini)()rtiiiit i)r<)i)erties ])ertaiiiiii<i; to tlieiii, in addition 

 to their abihty to inultii)ly and grow as above indicated, shouhl receive 

 attention, in onh'r tliat hiter a comparison of reproductive methods can 

 l)e instituted. It is found that if, in the case of many plants, a stem 

 be laid prostrate in the soil, its connection with tlie parent not destroyed 

 (P'ig. 2), its nodes, in addition to jwoducing branches (a), may develop 

 roots (/;) similar in structure and function to those of the parent. If 

 now the phytomers be sei)arated through some portion of the internode, 

 they will heal the wound so produced by the formation of a callus (c), 

 continue to grow independently, and become plants similar to the parent. 

 Such a process, here of artificial production, is of frequent natural 

 occurrence and is called Propagation. It is seen to be, in this case, 

 purely vegetative, and may be defined as the production by vegetative 

 processes of a plant-body growing independently and separately from 

 that from which it was derived. 



Fig. 2. Propagation by layering, a, axillary bud developed into a stem; b, adventitious roots; 



c, callus. 



Various other modes of stem-propagation may here be referred to, 

 and it may be remarked that the process is not confined to the node, 

 occurring in exceptional cases from fragments of the internode, root, 

 or even leaves. The phytomers, instead of remaining attached during 

 the rooting process (Layering), maybe first separated (Propagating by 

 Cuttings). The cutting, in this case called a Scion, may be inserted 

 (Grafting) or a bud may be so inserted (Budding) imder the bark of a 

 living stem, or it may be caused to take root in the soil. Propagation 

 by tul)ers or parts of them, as in the case of the potato, is identical. 

 It may be remarked, in passing, that in tlic seed itself nature resorts to 

 a similar method, for the contained embr\() consists of one or more 



