THE PROPAGATION OF SOME TREES AND SHRUBS 

 BY CUTTINGS 



By William L. Doran, Research Professor of Botany 



Research on the propagation of trees and shrubs by cuttings, a subject 

 of particular interest to nurserymen and, increasingly, to foresters, has 

 been stimulated in recent years by the coining into use of certain root- 

 inducing substances and considerably more has been learned than merely 

 how to use such substances. Much remains to be learned but, for the 

 convenience of propagators and other investigators, some of the results 

 are now brought together. 



Work done here and described below has involved the rooting of cut- 

 tings of 122 species, some of them represented by a number of varieties 

 and hardly two of them exactly alike as regards requirements for best 

 rooting. Some of the more noteworthy of these species, either because 

 cuttings have been considered especially difficult or slow to root or because 

 there has been so little information about their propagation by cuttings, 

 include white cedar, red cedar, incense cedar, white pine, Pfitzer juniper, 

 Asiatic sweetleaf, Japan quince, American elm, and species of Magnolia, 

 Corylopsis, Hamamelis, Fothergilla, Poncirus, H^lwingia, Stewartia and 

 Idesia. 



No brief and general conclusion, other than that different species 

 respond diflferently, is now attempted, for factors which afifect rooting 

 include the species (or even variety) itself, the type or condition and 

 time of taking of cuttings, concentrations and methods of applying root- 

 inducing substances if any are used, the rooting medium, and environ- 

 mental conditions (temperature, light and moisture) during rooting. These 

 and other factors are separately considered below, following which there 

 is a list of species (names taken from Rehder (84)*) the cuttings of which 

 have been rooted here or elsewhere by the methods mentioned in con- 

 nection with each. Common names are used when there are any and 

 an index is appended. 



It is not to be assumed that all species named are best propagated by 

 cuttings rather than by other means — seeds, grafting or layering for 

 example. But if cuttings are used, and if they are taken and handled or 

 treated as described, results to be expected should be about as indicated. 



Unless stated to the contrary, cuttings were rooted in greenhouses or 

 under glass and were not treated. Treatments, as will be seen, are not 

 always worth while. Cuttings designated as "treated" were treated with 

 a root-inducing substance, indolebutj'ric acid unless otherwise indicated. 

 Time of taking cuttings and treatments described are those which gave 

 the best results or, in some cases, the only ones tried. The emphasis is, in 

 general, on methods which were successful or relatively successful rather 

 than on those which were not. 



Cuttings which are described as rooting better, rooted in larger per- 

 centages than did the cuttings with which they were being compared. 

 In referring to work done here, percentages recorded, unless otherwise 



•Numbers ia parentheses refer to Literature Cited. See rage 41. 



