AGRICULTURAL BULLETIN 
OF THE 
STRAITS 
AND 
FEDERATED MALAY STATES. 
No. 5.j MAY, 1911. H 7 ol. X 
THE OCCURRENCE OF BURRS ON THE TRUNK 
OF HEVEA BRASILIENSIS. 
By Keith Bancroft, b.a., Assistant Mycologist, F.M.S. 
For several years repeated attention has been called to the 
.occurrence of excrescences or burrs on the trunk of Hcvea Brasiliensis. 
These excrescences not only interfere with smooth tapping, but may 
attain such dimensions as to render the surface untappable and to 
necessitate the transference of the tapping area to the upper parts 
of the trunk. They were first recorded in the “ Tropical Agricultu- 
ralist ” of September, 1905, and have since been discussed by Fetch 
in Circular No. 18, 1909, of the Royal Botanic Gardens, Ceylon. 
Burred trees are commonly met with in the Federated Malay 
States; the/ occur alike on high and on lowland, on well drained 
and on badly drained soils. The burrs are referable to two distinct 
sources and will, therefore, be dealt with separately. Those of the 
one type, although apparently stimulated by wounding, occur on 
untapped as well as on tapped trees and cannot, therefore, be said to 
be due entirely to any artificial stimulus ; while those of the other 
type are distinctly the result of wounding. 
Burrs of the First Type. 
These are far more important than those of the second type; 
The earliest record of their appearance is on trees of four years of 
age which had not been tapped ; they are most frequently met with, 
however, on trees which have passed the age of first tapping, and 
they can be seen to best advantage on old trees. 
