7(51 



NOTES ON THE COLOURATION OF THE YOUNG 

 FOLIAGE OF EUCALYPTUS. 



By J. H. Maiden, I.S.O., F.R.S., F.L.S. 



Most people have noticed, particularly during the winter and 

 early spring, that on the young branchlets, the foliage of 

 Eucalypts is, in some species, of a brilliant colour, shades of 

 crimson and purple being the commonest. 



There are few allusions to the character in botanical literature, 

 one of the few being the following: — 



' ' Then again, the red color of new foliage, so commonly seen here, 

 is an outward sign of adaptation, in that the color apparently acts as a 

 screen to prevent the chemical rays of light (blue end of the spectrum) 

 from penetrating the living workshops ; their admission to the young 

 leaf cells would he detrimental ; whilst the heat rays (red end) are col- 

 lected and thus secured as likely to help along the life processes more 

 rapidly to remove the new growth from babyhood to maturity."* 



Some years ago it entered into my. mind to collect data as to 

 the colours in question, but I found practical difficulties arising 

 from the fact that the colours that we see on the living plant alter 

 in tint within a few hours after removal. I then tried taking 

 the register of colours to the trees themselves, but found the stan- 

 dard work I have adopted (Dauthenay's "Repertoire de Coul- 

 eurs") so heavy that it was out of the question to carry it far in 

 the bush. Accordingly I submit some notes only on plants 

 growing wild or cultivated in the Sydney district, but I feel that 

 observers who desire to continue the work may get over the diffi- 

 culty in many cases by packing the leaves in closely shut tins, 

 and posting them, provided that they are not longer than a day 

 or two in the receptacle. 



*C. T. Musson in "The Hawkesbury Agricultural College Journal," 

 March 25, 1905, p.f,8. 



