280 BOTANICAL GAZETTE [APRIL 
photograph of the older clump shows trunks about six inches in diameter, 
which seems to be the maximum, after which the old trunks die and are 
Betula, n. sp. 
?, showing characteristic habit; collected near Boulder, Colorado, 
by D. M. Andrews. 
replaced by young sprouts from the same root. While the difference in 
size (between this and B. papyrijera) may be due to differences of environ- 
