PKOPAGATLfTG BY LATEES. 176 



from the wounds made on tlie layered parts, and the sap 

 flowing from these wounds will often corrode and other- 

 wise injure the exposed ceUs and entirely prevent the 

 production of roots therefrom. Wounds made in the 

 branches of coniferous trees during the winter and early 

 spring months are usually soon covered by the exuding 

 resin, the severed and otherwise exposed cells thereby 

 becoming fully protected, not only against the influence 

 of moisture from without, but it eflectually prevents 

 the formation of a callus and production of roots. For 

 this reason, such conifers as Pines, Spruce, and Firs 

 should always be layered at a time when the sap is thin- 

 nest and flovring most rapidly, as during the flist growth 

 of spring and early summer. With some kinds of hardy 

 deciduous trees and shrubs the autumn is the better sea- 

 son in which to make layers, for the reasons given for 

 making cuttings at that season, but such variations will 

 be noted further on. The advantages and disadvantages 

 in propagating plants by layers are : 



First, It is a very simple process of multiplying plants 

 by which an inexperienced person may propagate many 

 species and varieties that require greater skill by different 

 processes ; in other words, it is especially valuable to 

 amateurs who possess neither skill nor facilities for propa- 

 gating plants by the more advanced and superior modes. 



Second, It is a certain mode, with by far the larger 

 number of ligneous species, as the parent plant sustains 

 the layer until it has produced roots through which it 

 may, when transplanted, derive nutriment for self-sup- 

 port ; but the roots produced on layers are seldom of as 

 firm a texture, neither do they, mature as early as these 

 produced on cuttings : hence their inferiority. 



Third, With many kinds of plants much larger speci- 

 mens may be obtained in less time than is possible by 

 cuttings, and, as size is frequently more highly appre- 

 ciated tbau quality, large lasers are ueuallj in demand, 



