160 THE INSTABILITY OF LEAF-MORPHOLOGY, 



genus on foliar characters, with special leference to venation 

 and texture. In (S; 1900, p. 595) he applies the test of brittle- 

 iiess to the phyllodes as a differentiating character between two 

 closely allied species, incidentally mentioning that this test 

 is of no value in dried specimens. In a later paper,(5; 1900, 

 Mr. Cambage returns to this subject, and notes (p.7l9) that 

 the species A. homalophylla A. Cunn., "Yarran," whose 

 foliage was, by its clean break, separated from A. Cambayei 

 R. T. Baker, " Gidgea," shares this character with A. pendula 

 A. Cunn., "Myall," similarity in phyllodic texture between 

 them being also noted. In his description of A. drfformis, 

 the author, Mr. R. T. Baker, F.L.S., (3; 1897, p. 154) con- 

 siders it necessary to explain, at some length, the differences 

 in foliar characters between his species and A. penniiiervis 

 Sieb., to avoid confusion between them, referring also to 

 the variability in foliage found in the latter species and its 

 vars. Examples of the pinnate-leaved A. discolor Willd. (13- 

 1915, p. 209) collected from a series of plants growing in company 

 on the slope of a hill at Cook's River, emphasised the irregularity 

 of the number of pinnae, relied upon by Bentham (4; ii., p. 318) to 

 differentiate two groups, the range of the size of tlie leaflets as 

 given in the description of this species {I.e., p. 4 14) also display- 

 ing insufficient elasticity. A. implexa Benth., (13; 1915, p.415) 

 furnished evidence, by means of a series of phyllodes taken from 

 a small colony of some half-dozen plants, evidently with a com- 

 mon parentage, growing on a sandstone-hill at Glenbrook, of 

 morphological, foliar divergence within this species, more pro- 

 nounced than that differentiating it from A. Maideni F.v.M. 

 the texture, and venation of the foliage of these two species 

 showing similarity. Dimorphic foliage, the result, in some 

 instances, of seasonal growth, is not infrequent in this genus. 

 Examples showing the lower phyllodes larger than the upper 

 ones, others again with the larger phyllodes uppermost, and a 

 specimen with two, opposing branches on a single stem wliose 

 phyllodes showed a considerable divergence, wei'e noted (13; 1914, 

 p. 6 48). Variation was also noted in the phyllodia of A. elon'gata 

 Sieb., (13; 1914, p. 397) and those of A. suaveoleiis Willd., of which 



