609 



PLATE 246 (Figs. 5-9). 



A Secondary lntramarginal Vein. 

 Mr. E. Cheel has drawn my attention to the vein which is parallel and close to the margin in some 

 specimens of E. radiata, and which is distinct from the looped or irregular secondary vein, which really 

 ■consists of the curved ends of the secondary veins, which, at their other ends, join the midrib, He suggests 

 that it may have some taxonomic value. As it occurs in the leaves of various forms of this species, as 

 shown in the drawings, and also in the widely separated E. sideroxylon and E. conica, both reproduced, 

 and in, e.g., E. Sieberiana, and in some other species (it is overlooked because it is usually so minute, and 

 at times very close to the margin), I think it is rather to be looked upon as a simple morphological character — 

 a mechanical necessity to support the leaf-tissu« in leaves of varying thickness and width. Following 

 are some figures of leaves showing this faint secondary lntramarginal Vein : — 



Fig. 5. E. radiata Sieb. Ashfield, near Sydney, N.S.W., a cultivated plant raised from seed obtained 

 from Wyndham, N.S.W. (E. Cheel). ■ 



6. E. radiata Sieb. Bellimbella, near Nerrigundah, N.S.W. (E. Cheel). 



7. E. radiata Sieb. Mittagong, N.S.W. (District Forester C. J. Clulee). 



S. E. sideroxylon A. Cunn. Harvey Range, near Peak Hill, N.S.W. (J. L. Boorman). 

 9. E. conica Maiden. Cowra, N.S.W. (R. H. Cambage). 

 All the leaves juvenile or nearly so. 



PLATE 247. 

 DECURRENCE. 



1 . Of the Midrib. 



Where the branchlet (rachis) is markedly angular (quadrangular) it is commonly seen that the petiole, 

 or continuation of the midrib, is decurrent and expanded, its outer edges forming the quadrangular edges 

 of the branchlet. For examples see figs. 1-4, Plate 247. 



I have some notes on "Angularity of Branchlets " at Part LVI, p. 315. The state of being 

 decurrent is always accompanied by angularity of the branchlets. 



2. Of the Leaf. 



It is a much rarer case for the tissue of the leaf or lamina to expand (not to the full width of the 

 lamina), at the place where the petiole would normally be. In such a case the midrib is seen distinct 

 from the lamina and often thickened, e.g., 3a-3c, Plate 236 (E. Flocktoniai). In no species of Eucalyptus 

 hitherto recorded is the lamina so expanded at the base as in the present one. In cases in which there is 

 no obvious decurrence of the lamina, e.g., figs. 1-4, Plate 247, the midrib is distinctly seen decurrent on 

 the rachis, and., in addition, angles decurrent from the margins of the lamina. In other words, 

 contemplation of figs, lb and lc show that there is decurrence of both midrib and lamina, but in most cases 

 the lamina (as regards decurrence) is suppressed. 



In E. Flocktonice the decurrent portion of the lamina is adnate to the rachis. So also is the midrib 

 in this and other species figured. No doubt a future botanist will make sections and illustrate the 

 anatomical relations of the decurrent part of the lamina to the decurrent part of the midrib to the rachis, 

 and of the two latter organs to each other. See also Part LIX. 



la, lb, lc. Intermediate leaves of E. longicomis F.v.M., Wagin, W.A. (C. A. Gardner, No. 1234). 

 lb and lc enlarged. 



These exhibit decurrence of the midrib down the rachis, while the outer portions of the lamina 

 most remote from the midrib are decurrent also, and develop a more or less winged rachis. 



2a, 2b. Intermediate leaves of E. longicomis F.v.M., Westonia, W.A. (Forester J. M. Cusack). To be 

 compared with figs, la -lc. 



