38 president's address. 



cyanophylla), "lower phyllodia (i I(j Id iu. long" (.1. LiiuUeiji), '"3-10 in. loag 

 or even more'' {A. iiachycarpa), and others, as describcil by Bentliani? 1 have 

 euphyllodes of .1. lonyifolia up to 13J inches long, and lA broad; and Maiden 

 has recorded a variety of this species with phyllodes, so-called, up to 20 inches 

 Jong. Allowing one-third of the total length for that of the petioles, euphyllodes 

 l'2-"20 inches long — if they are simply thittened petioles which have lost their 

 blades — should belong to potential bipinnate leaves 3 to 5 feet long! 



The euphyllodes of Australian Acacias may be short or they may i)c long. 

 If very short, they are the Hattened axes of species, which, if they had not be- 

 eonic euphyllodineous, would have only a few (1, '2, or 3) pairs of pinua^. If 

 long, under similar circumstances, they should liavc numerous pairs of piimse, as 

 sliown in my i)hotograplis |Pls. v.-vii.) of leaves of reversion-shoots of a species 

 with long eupliyllodes, up to 8| (PI. ii., fig. 1) inches long, or even longer. But 

 flattened petioles of leaves of Anstralian Acac'ias, which have lost their blades, as 

 long as 12-20 inches, are mythical structures; and the idea that there are, or may 

 be such is nothing less than fantastic I 



The current idea that the euphyllodes ol' Australian Acacias are simiily 

 flattened petioles which have lost their blades, is a barren conception which has 

 retarded the progress of knowledge. If that is all they are, one is ])reclu(led 

 from discussing the question of what sort of bipinnate Acacias the eu])hvlhMlineous 

 Acacias would or might be if they did not develop euphyllodes. 



But when it is realised that the euphyllodes are the Hattened, ]iriniary leaf- 

 axes or common petioles of bipinnate leaves which liave lost their pinn;e, it be- 

 comes possible to reconstruct them theoretically in a very simple way, and then 

 to find analogues of them among the existing Bipinnatfe, since these itu-lude 

 Acacias of wiiich the adult leaves have — one pair of i)innie only, "on a common 

 petiole of about I inch long," as Bentham records of .1. Gilberti, or "1 or 2 pairs, 

 the common ])etiole about 1 incli" (.1. suliemsa). or any number of pairs up to 

 "usually 10 to 20 i)air.s" (.1. deulbatu, length of coMuiion jietiole not stated), or 

 "15 to 20 pairs, the common i)etiole 2 to 3 in<-iies" (,1. BidwilV), or piissil)ly 

 even more, if one were to search carefully oxer abiuidance of material. 



The simple method of reconstructing them is, to nu'asure with a pair of com- 

 passes the length, from tip to ti]) across the partial iliachis, of a good ])air of 

 op])osite, expanded leaflets on the l)ii)innate leaves of a seedling. Tiiis will give 

 approximately the length of an internode. Then measure off the internodes on 

 a eujiliyllode, beginning at the apex, and what is over, regard as the iietiole. 

 This will enable one to calculate approximately the ])ossible number of jiairs of 

 pinnas tiiat could be present. If one can get a scc<lling with a leaf with two 

 pairs of pinnae, one can comimrc' the leniilli of tlic intei-nodc with llie length 

 of an opi>ositc jiair of leaflets. Hax'ing done tliis, then look tor the bipinnate 

 analogue among the l)ipinnate s])ecies described by Rent ham, or others, and 

 figured in Mueller's "Iconoi;ra|)hy of the Acacias," or elsewhere. But. of course, 

 reversion-foliaiie. and es])ecially i-cversion-shoots. if one can get good S|)ecimen.s, 

 will show N'alurc's method of actually doing it. 



Hk\HRS10\-1''0I,IAGK, KeVKRSI0N-Si1(X)TS, .\NI) SrCKKRS. 



Textbooks sometimes nu'ution, in an in<leHnite way. the occurrence of rever- 

 sion-foliage on euphyllodineous Acacias which have lieen pruned or otherwise in- 

 jured, Lubbock and Tiiom<5"s figure si)rays of,!, melunoxylon, with bolli eu))hyl- 

 lodes and bipinnate leaves: and other authors menti(m similar peculiarities. This 



