385 



The Artificial Production of Vigorous Trees by Hybridisation. 



Althoiigh written without Eucalypts in view, a paper bearing the above title 

 by Dr. Augustine Henry, Lecturer in Forestry in The University of Edinburgh, in the 

 London " Quarterly Journal of Forestry " for 1921, is worthy of attention by 

 Australian foresters, if only because of the fact that most of the Algerian and New 

 South "Wales hybrids are reputed to be especially vigorous, and to possess specially 

 durable properties in their timbers. The following extract, showing the scope of the 

 paper, may be sufficient for my present purpose :— 



For several years the author has been making experiments in the production of new trees by 

 hybridisation in the hope of obtaining fast-growing kinds that would produce timber rapidly. A con- 

 siderable number of such trees has occurred accidentally, and among them maybe mentioned the Lucombe 

 Oak, the Huntingdon Elm, the Black Italian Poplar, the Cricket Bat Willow, and the London Plane. All 

 these show the striking feature of first crosses in the difference of the rate of their growth from that of the 

 parent species. These hybrids of the first generation, in trees as in other plants, are remarkable for their 

 size, rapid growth, early and free flowering, the ease with which they can be multiplied, and, in all 

 probability, their comparative immunity from disease. Impressed with these facts, the author urged in 

 1910 that the artificial production of trees by crossing was a new and important field of research. 



Effect of Rapidity of Growth on Timber. — It is a popular belief that fast grown timber is necessarily 

 soft and comparatively worthless. This is a fact in most conifers ; but in one class of broad-leaved trees 

 the wood of which is characterised by large pores, in the inner part of the annual ring, the contrary is true^ 

 as the faster the timber of these trees is grown, the stronger and denser it becomes. This class includes 

 Oak, Ash, Chestnut, Hickory, and Walnut, the species, in fact, that, par excellence, produce the most valuable 

 timber." 



Oak grown in the Sydney district is inferior in quality, speaking generally, 

 but the rapidity of growth requires investigation. As regards the quality of Eucalyptus 

 timbers grown with various degrees of rapidity, we have practically no data at present. 



