64 



Some species so included in Bentham's time are now knowTi not to be sessile 

 throughout life, and it is very possible that, as time goes on, it will be found that all 

 Eucalypts are heterob^astic {plastos, a shoot), i.e , having juverile leaves different from 

 mature ones. This, if proved, will come about in two ways, by (a) the discovery of two 

 kinds of leaves on existing isoblastic species, or (b) the discovery of two species (now 

 accounted isoblastic), one with cordate, &c., leaves entirely, and the other with usual 

 falcate, &c., leaves entirely to be conspecific. 



We have much to learn in regard to the effect of changed environment on different 

 species of Eucalyptus, and experiments in cultivation have thrown, and yvHl continue 

 to do so, much light upon variation in this direction. 



So far as I know, the only species of Eucalyptus (in addition to the present one) 

 which are isoblastic are : — 



1. E. pulvigera A. Cunn. A rare New South Wales species. [By this E. ful- 

 verulenta Sims is meant. See Plate 91, Part XXI of the pres< nt work.] 



2. E. cordata LabUl. A Tasmanian species. [See Plate 84, Part XIX.] 



3. E. macrocarpa Hook. A very coarse Western Australian species. [See 

 Plate 77, Part XVIII. In Journ. Roy. Soe. N.S.W., liii, 70 (1919), I have drawn 

 attention to the fact that there is a tendency to heteroblasticity in this species.] 



4. E. pruinosa Schauer. Indigenous to Western Australia, North Australia, 

 North Queensland. (I have seedlings of this species raised from seed collected by Prof. 

 Bald^^nn Spencer, at Whanalowra (?), Northern Territory, in 1903, which are distinctly 

 pedicellate ! ) [See Plate 54, Part XII.] 



5. E. ferruginea Schauer. With sessile, cordate, rusty pubescent leaves — an 

 Angophoroid species from Western Australia and North Australia. 



6. E. setosa Schauer. A sessile, cordate, Angophoroid species, ^dth bristly 

 branchlets, from Queensland and North Australia. [The figures on Plate 158, Part 

 XXXVIII, show that E. setosa cannot be longer considered as isoblastic, and that Plate 

 159 shows that E. ferruginea is becoming heteroblastic, and that probably more active 

 observation wall produce additional evidence in that direction.] 



Then we have, in a class by itself : — 



7. E. perfoUata R.Br., with very large perfoliate, connate leaves and fruits. In 

 this case two opposite leaves cohere into a single lamella, which is pierced by the stem. 

 From Western Australia. [See Part XLIV.] 



8. E. gamophylla F.v.M., as figured by Mueller in " Eucalyptographia," shows 

 no stalked leaves, but it becomes eventually lanceolate and very shortly stalked. See 

 a specimen from Central Australia, collected by C. Winneckc about 1884 (Herb. Melb.), 

 thus leaving E. perfoUata the only connate-leaved species to date. [See Plate 147, 

 Part XXXV of the present work.] 



9. E. peltata Benth. is worthy of special mention. Its leaves are alternate, 

 peltately attached to the petiole above the base, and broadly ovate. This unique 

 species is figured in " Eucalyptographia," and morphologically it is an incipient 



