280 



at a little distance, the tree .appears to have a composite trunk with two kinds of bark, 

 and to have two kinds of foliage, as represented by two large branches of the different 

 species concerned. 



There is a fine example of this inarching of branches, 12 inches in diameter, in. 

 E. hcemasioma var. micrantha in the Federal Territory, on the Queanbeyan-Uriarra 

 road, near the saddle of Mount Stromlo. Mr. C. J. Weston pointed me out the tree 

 and sent the photograph (February, 1920), which will "be subsequently reproduced. 



There is another illustration of cohesion of branches in the figure of E. rostrata 

 by A. D. Hardy, Plate XI, Proc. Roy. Soc. Vict., xxix (New Series), 167 (1916). 



" An excellent instance of fusion of shoots (post-genital) was observed in the 

 case of E. salmonophloia; two cross-bars occurred, one close above the other; a very 

 rare case." (" Principles Plant Teratology," Worsdell, i, 118). 



It will be observed that all the Eucalypts quoted are Gums, or, if rough barked 

 on the trunk, with smooth branches. In an allied genus, Angophora, A. lanceolata is 

 perhaps the commonest tree in Eastern Australia to show the phenomenon, and that 

 is a smooth bark also. In the case of the rough barks, it is fair to suppose that the fusion 

 took place at an early stage of the plant's history, before the rough bark had developed. 



" Naturally grafted branches are fairly common on Beech, Oak, Holly, Lime, 

 Willow, Yew, and Scots' Pine, whilst they may also be noted on many other trees." 

 (" Natural Grafting of branches and roots," by W. Dallimore, Kew Bulletin, 1917, 

 p. 303). Mr. Dallimore discusses the way in which this grafting has been brought 

 about in certain cases. Speaking of the friction between two branches, caused by the 

 wind, he points out that a good deal of tissue may be destroyed, and all the time 

 nature is trying to repair the injury by forming patches of callus on both branches, 

 at those places where friction is least active. As the branches become heavier and 

 movement ceases, the patches of callus grow together, and eventually a strong union 

 is effected between the two branches. The paper is suggestive, and should be referred to. 



2. Adhesion of Branches. 



Under Cohesion of Branches," at p. 279, I have quoted a paper from my pen, 

 and it will be seen that the Natural Grafts there enumerated are vastly more 

 numerous in the case of Adhesion, i.e., where two different species (and more rarely, 

 genera) are concerned. I will content myself with a few supplementary notes. 



Following is a relatively early reference to natural grafts. " If nature does 

 not admit of crossing in the genus Eucalyptus, it certainly encourages that of grafting, 

 for, in the neighbourhood of Mudgee, the Apple {Angophora intermedia) may be grafted 

 naturally on E. rostrata, whilst, on the Richmond Common a similar eccentricity may 

 be seen on E. tereticor-nis." (Rev. Dr. Woods in Proc. Linn. Soc. N.S.W., xvi, 61, 1891.) 

 I have not seen the reputed Mudgee graft, but that on the Richmond Common was a 

 false graft, in other words, no graft at all. See my " Forest Flora of New South Wales," 

 vol. vi, p. 79. 



