HYBRIDISATION IN THE GENUS. 



A.— HISTORICAL. 



The following notes are given, as far as convenient, in chronological order : — 



Caley (1800-1810).— In Agric. Gaz.,N.S.W., xiv, p. 988, October, 1903, I have 

 an article " George Caley, Botanical Collector in New South Wales, 1800-1810," which 

 contains determinations of Eucalypts based on some of Caley's specimens in the Vienna 

 Herbarium. At p. 990 it is recorded that Caley gives the name " Burryagro — A hybrid 

 between Barilgora and Derrobarry " — to the species E. Boormani Deane and Maiden, 

 which (Proc. Linn. Soc, N.S.W., xxvi, 339, 1901), we had expressed the opinion might 

 be a hybrid, although in ignorance that Caley had expressed a similar opinion nearly 

 a century before. Now " Barilgora " was the aboriginal name for E. hemiphloia F.v.M. 

 and " Derrobarry " for E. siderophloia Benth. 



The blacks had but one name for E. Boormani and for E. siderophloia ; but 

 Caley saw they were different, and his surmise as to hybridisation was marvellously 

 shrewd. He was undoubtedly the discoverer of hybridisation in this genus. He 

 studied the trees in the bush, made his pronouncement, and produced his specimens 

 to back up his statement. Compare also, in connection with E. Boormani (Proc. Linn. 

 Soc, N.S.W., xxv, 339, 1901; op. tit., xxx, 494, 1905). 



In my work, " Sir Joseph Banks, the Father of Australia," p. 140, I say — 

 " Recently I dedicated a New England Ironbark, Eucalyptus Caleyi, to his memory, 

 to remind botanists of his discovery of hybridisation in the genus, in which he showed 

 an Ironbark to take a part." 



I followed up my Agric. Gazette paper (1903) by what may be termed a 

 manifesto conveying whole-hearted belief in hybridisation in the genus. This was a 

 paper in Rep. Aust. Assoc. Adv. Science, vol. x, pp. 297-303, 1904, which was translated 

 into French, and published in Rev. Hort. de VAlgerie, Sept., 1905, pp. 211-216. 



Bentham, 1863. — In his preface to vol. I of the " Flora Australiensis," p. 17, 

 Bentham, not specially referring to Eucalyptus, remarks : — ■ 



Little as we know, for instance, of the influence of natural hybridising in Europe, it has been still 

 less, if ever, observed in Australia ; and many other causes may have produced apparent passages 

 between species really distinct. I have, therefore, whenever there is a difference of opinion between 

 Dr. Mueller and myself, adopted the conclusion which has appeared to me the most probable, and 

 mentioned the objection to it for the consideration and, if possible, the decision of future botanists. 



The best known Australian case of description of a non-Eucalyptus hybrid as 

 a species is that of Brachychiton populneo-acerifolium F.v.M., in Journ. Linn. Soc, 

 N.S.W., ix, 379 (1884). 



