Postscript xxiii 



of the history of the Lucombe Oak and its descendants, have thrown much light on 

 a class of trees, which though common in cultivation on account of their vigour of 

 growth, are unknown in the wild state. 



These trees undoubtedly originated as chance seedlings, due to accidental 

 cross - fertilisation of two distinct species, and were immediately selected by 

 observant nurserymen as desirable varieties to propagate. Trees like the Black 

 Italian Poplar and the London Plane, which in botanical characters appear to be 

 first crosses in each case, between an American and a European species, can be 

 traced back to 1700, about which date the introduced species was long enough in 

 the country to produce flowers and to fertilise the native species growing beside it. 



Other trees, which I consider to be also first crosses, on account not only of 

 their botanical characters but because they are unknown in the wild state, are : 

 the Common Lime, Huntingdon Elm, and Cricket-Bat Willow, the parents in their 

 case being closely allied European species. All the preceding hybrids were pro- 

 duced accidentally ; and similar cases occur periodically in certain nurseries, as at 

 Plantieres, near Metz, where two splendid hybrid poplars {Populus Eugenei and 

 P. robusta) have been picked out of the seed-bed. The first to produce artificial 

 crosses between forest trees was Klotzsch in 1845 ! ^'^^ his experiments, though on a 

 small scale, were successful in indicating that extra vigour of growth was obtainable 

 with certainty. 



Practically nothing, however, has been done, since his time, to improve the 

 breeds of forest trees ; and foresters have never even thought of the possibilities 

 in this direction, though gardeners and farmers have shown the way for centuries. 

 I suggested in a paper read on 7th April 19 10 before the Linnean Society that 

 artificial crossing should be tried in the Ash and Walnut, as the quality of the wood 

 of these two valuable trees would be improved by more rapid growth. 



During the past three years I have carried on cross-pollination of trees of 

 certain kinds at Cambridge, in Kew Gardens, and near Exeter and Gloucester. These 

 experiments have shown that there are obstacles in the way of obtaining successful 

 results, owing to the difficulty of manipulation on trees swaying in the wind, and 

 to the spring frosts which often injure the pollinated flowers. Moreover, suitable 

 exotic trees, especially of the broad-leaved sorts, are hard to find, as those that exist 

 rarely produce good flowers. I am convinced that such experiments could be carried 

 on much more successfully in stations like Montpellier in France, or Washington in 

 the United States, where suitable trees and a warm climate can be readily found. 

 Nevertheless, I have raised a considerable number of hybrid seedlings, which 

 are now under observation. First-crosses once obtained can readily be reproduced 

 by cuttings or by layers ; and the cost of propagation would be very moderate. 

 That this is feasible, is shown by the splendid hybrid elms in Belgium and Holland, 

 all of which are raised by layering in nurseries. 



Many interesting problems, which had to be laid aside for the time, arose in 

 the course of the researches which were undertaken in the work of preparation 

 of the seven volumes. To some of these problems, especially those connected with 

 the origin of sports and varieties, I hope to return. The belief is rapidly gaining 



