75 
reverts to the normal type, forming a tall, symmetrical, columnar top. In this case no knees arc 
developed. The difference in the form of the top developed in the swamp and that developed on uplands 
or in parks is evidently due to the difference in food supply, as in the case of the Jumper. (Year book, 
Dept. of Agric., U.S.A., 1896, pp. 94 and 95.) 
Speaking of " knees " in Cypress-trees, Coulter, Barnes, and Cowles, ii, 508, say : 
" Oddly enough, knees do not develop in deep water, but only in shallow water or in 
swamps. If these peculiar structures are regarded as reactions to a slight oxygen 
content, it is difficult to account for their absence in deep water, unless it is supposed 
that the life- conditions there are too poor to permit of growth." 
Knees are not formed on Taxodium in the Botanic Gardens, Sydney, under any 
of the conditions under which we grow them. 
PHOTOGRAPHIC ILLUSTRATIONS. 
Three photos by W. C. Grasby, Western Australia, of Eucalyptus rudis, viz. . 
No. 1. Flooded or Blue Gum. Ferndale, Balingup, W.A. Has been ringbarked seven or eight 
years, and kept alive by developing an aerial root 7 feet from ground, and sending it down 
through decayed interior. See No. 2 of base of the tree showing the root. 
No. 2. Base of Blue or Flooded Gum, showing aerial root developed 7 feet from ground, and sent 
down through decayed centre of tree. See No. 1. 
No. 3. Base of small Blue or Flooded Gum at Ferndale, Balingup. Ringbarked a number of 
years and has developed roots from above the ringing. (See fuller references at p. ). 
A giant Fig on the Brunswick River showing adventitious roots. (W. F. McLean, photo). 
Roots from River Gum Stumps (Eucalyptus rostrata). Menindie, Darling River, N.S.W. (Judge 
Docker, photo). 
Edge of clearing. Native forest removed for pasture. Lord Howe Island. Shows adventitious roots 
of Screw Pines (Pandanus}. (A. R. McCulloch, photo). 
Two sketches showing adventitious roots of Fig Trees. Illawarra Ranges, 1853. (From original 
pencil drawings by the late J. F, Mann). 
