124 TRANSACTIONS OF ROVAL SCOTTISH ARBORICULTURAL SOCIETY. 



It would be idle to maintain that " new creations " are 

 only now appearing among trees, and we know quite well that 

 many such hybrid creations among flowers and fruits have long 

 been in existence, although many of them have been obtained 

 by most haphazard and often inexplicable ways. But, as 

 Professor Henry remarks, " it is remarkable how little has this 

 method been applied to the improvement of forest trees." 

 Klotzsch commenced the work in Berlin in 1845, ^^"^ ^^ 1891 

 the Californian hybridist, Luther Burbank, obtained some truly 

 remarkable results in rate of growth in the progeny of some of the 

 walnut species which he crossed. In fact, Burbank seemed to 

 believe that almost anything was possible in this way. "The 

 possibilities of improvement in trees are so great," he said, "as 

 to make it seem almost an exaggeration to state them," and he 

 expressed the opinion " that one of the most important, in some 

 ways the most important of all the many fields open now to the 

 plant breeder, is this one of the production of new and the 

 improving of old trees," and that he believed it to be "of 

 immense significance commercially." 



From the results obtained by Professor Henry, it would almost 

 seem that the possibilities adumbrated by Burbank were not over- 

 drawn, so amazing are they. One of the most remarkable is a 

 hybrid poplar {Populus genefosa, Henry), a cross between the 

 Carolina poplar (P. angulata $) and P. trichocarpa ((^), the 

 female parent being one of the black poplars, and the male 

 belonging to the balsam section of the genus. Plants of this 

 hybrid raised from seed sown in June 1912 were from 2 ft. ti ins. 

 to 3 ft. 6 ins. high by the end of 19 13, and two of them, 

 which were not transplanted, and therefore not checked, were 

 l\ feet and 10 feet high respectively at the end of the growing 

 season in 1914. The same female parent crossed with P. nigra 

 betulifolia (the common European black poplar with hairy twigs) 

 gave less vigorous seedlings (the tallest plants being now 

 4 ft. 5 ins. and 3 ft. 8 ins. in height), strongly resembling 

 in their characters the black Italian poplar {P. serotina) 

 and the Eucalyptus poplar [P. regenerata), hybrids of similar 

 origin which were produced accidentally in France many years 

 ago, and which Professor Henry says are now "the most 

 common poplars in cultivation." Many other hybrids have been 

 produced between species of ash, alder, elm, larch, cypress and 

 beech, and even crosses between species of different genera — 



