40 president's address. 



lode is relatively very short. I liave two examples of nearly complete eupbyl- 

 lodes, one of which has an apical pair of pinnae, and a large leaflet with an op- 

 posite pair of small ones, on the margin | inch from the base; while the other 

 has an apical pinna with two pairs of leaflets, and a marginal pinna with two 

 l)airs of leaflets, § inch from the base. Another specimen has one pair of pinn<e, 

 of which one has a terminal leaflet. I have one leaf with three complete pairs of 

 pinna;. 



Figs. 4, 8, 9, 10 show foUaeeous terminal setae. Two of them have mar- 

 ginal leaflets, and in one case, a pinna which shrivelled in drying. 



I am indebted to Mr. C. T. Musson for some very interesting reversion- 

 shoots from a shrub of A. podahjriaffolia, which had been cut back. These are 

 particularly interesting, because this species has sliort enphyllodes, which are 

 nearly as broad as they are long, up to IJ x 1% inches. Seventeen leaves 



16 



show no flattening on the lower side, and fifteen of these have two pairs of pinnai. 

 Three of these are figured. ( Plate vii., figs. 1-3. ) They all show much flattening 

 of the upper side of the leaf-axis up to the level of the lower pair of piunae, 

 and some flattening of the internode. But the lower, broad, flattened portion has 

 a loose end. The presence of the lower pair of pinnae, by retarding the flatten- 

 ing of the internodal contribution to the complete euphyllode and blocking the 

 ■way, left the portion below the lower pair of pinnae in the lurch, in all three 

 eases; and I have others more or less like them. Two examples, with one pair 

 of pinnae (PI. vii., figs. -1-5) show very well the rudiment of the terminal pinna, 

 without leaflets, with the terminal seta, which, in this species, unless accidentally 

 missing, is usually conspicuous on the early euphyllodes, and particularly on the 

 young ones. It is so long sometimes that, when dry, it twists. It is obvious 

 that, in this case, the euphyUode comprises two, or at the most, three, internodes, 

 and the petiole. If it were not euphyllodineous, this species would be a bipin- 

 nate Acacia with three pairs of pinna?, occasionally, perhaps, four at the most . 

 Cambage has recently described and figui'ed the seedling of this species [Part v. 

 of his papers] . 



The finest examples of reversion-shoots and suckers, I have yet seeu, are two 

 lots of A. implexa (?), which I quite casually met with in March, 1919: One 

 lot comprises specimens from two plants, 8-10 feet high, growing close together, 

 that had been badly scorched by a l)ush-flre, which killed the parts above gTound, 

 but without injury to the root-system. Reversion-shoots from the base of the 

 stems, and suckers from some of the roots came up freely. T fortunately found 

 them in the early stages; and specimens were taken, from time to time, over a 

 period of six months, until what were left had only euphyllodes, or a few bipinnate 

 leaves of no importance. The second lot was procured from some half dozen 

 plants at the side of a country-road, which had been miscliie\ii\islv broken or cut 

 off a little above the ground . 



From the complete collection, I have been able to select a sequence of leaves, 

 which include — (1) simply pinnate leaves, present on two suckers, but, if de- 

 veloped, missing on the reversion-shoots; (2) bipiniuite leaves with from one to 

 eleven actual or potential pairs of pinna;, some of the lowest pairs being repre- 

 sented by leaflets; and (3) the five late stages of the waning pinna?, and the wax- 

 ing flattening of the long conniion petioles or primary leaf-axes, shown in Plate 

 vii. The entire se(|uenee is not shown, my main object being to show as many as 

 possible of the best examples illustrating the inversely projiortional ratio in 

 which the two antagonists are represented at various stages. The sul)stitution of 

 flattening axes for piuu;e is not a case of "walk in. walk nut." It is an intense 



