1907] BRIEFER ARTICLES 279 
negative (film or glass) against the leaf, in either case permitting a very 
striking demonstration of the need for light in photosynthesis. 
Both instruments appear to be correct in principle; both are conven- 
ient and efficient in manipulation; and they yield most satisfactory results. 
—W. F. Ganonc, Smith College, Northampton, Mass. 
IS THIS BIRCH NEW? 
(WITH ONE FIGURE) 
The paper birch (Betula papyrijera Marsh.) has never been reported 
from Colorado. The nearest region to Colorado from which authentic 
specimens have been obtained is probably the Black Hills in northwestern 
Wyoming and adjacent South Dakota. It was therefore a great surprise 
when Mr. D. M. ANDrREws of Boulder, Colorado, reported finding a birch 
which in many respects resembles B. papyrijera. He writes of it as fol- 
lows: ‘‘About three miles from Boulder on the north slope of Green 
Mountain, altitude 6500-7000 feet, I find one hundred trees, more or less, 
of the species from which I send you specimens.” 
An examination of the material sent, which, by the way, was secured so 
late in the season that the specimens are not in good condition, indicates 
its affinity to B. papyrifera. It cannot be referred to the var. cordifolia. 
and it is even less like typical B. papyrifera. In the material so far avail- 
able, however, it is difficult to point out specific distinctions. From the 
latter it differs in the darker bark, which on the trunk is marked by long 
transverse rifts (lenticels). The current season’s twigs of ANDREWS’ speci- 
mens are light brown, the two-year-old twigs more or less grayish, and the 
older branches reddish brown and distinctly marked by the white oval 
lenticels. The bark on the main trunks is silvery gray, materially darker 
than in B. papyrifera, though it peels readily into layers as in that species. 
The leaves do not seem to differ essentially, being either broadly cuneate 
or rounded at the base. The margin is rather sharply and irregularly 
serrate, though the teeth are not long. The apex is somewhat abruptly 
short-acuminate. The bracts of the fruit are deeply 3-lobed, the central 
lobe being longer and narrower than the lateral. The nut is oblong- 
obovate, with very thin wings nearly twice as broad as the body. 
Its habit is perhaps its strikng character. In B. papyrijera there is 
usually a single trunk, which branches above in true tree fashion. AN- 
DREWS writes of his birch as follows: “‘ You will notice the uniform tendency 
to form clumps or stools, which is true of quite young specimens. The 
