168 Rhodora [SEPTEMBER 
to passed as B. lutea Michx. f. B. alleghaniensis, based primarily 
upon material from the upper slopes of Mt. Pisgah, western North 
Carolina, distributed by the Biltmore Herbarium as no. 1619, was 
given a broad range: * From Massachusetts to Quebec and northern 
Michigan, south to southern New York, Pennsylvania, and in the 
mountains to Georgia." Subsequently, in his North American Trees 
(1908), Britton made more definite his differentiation of the two 
Yellow Birches by stating the key-characters (p. 247): 
Fruiting scales 4 to 5 mm. long; leaves mostly cordate 
14. B. alleghaniensis. 
Fruiting scales 8 to 10 mm. long . . . ; leaves rarely cordate 
15. B. lutea. 
On pp. 258 and 259 of the same work, where the two are more 
fully described and illustrated, B. alleghaniensis is shown with the 
leaves very definitely not cordate, with scales there described as “4 
to 6 mm. long" and having “the wedge-shaped part below the lobes 
very short" and the fruits cuneate-obovate; while B. lutea, assigned 
a more northern range, has the scales with prolonged “stalk-like part 
below the lobes" and the fruits suborbicular. "Though recognizing 
the two extremes indicated by Dr. Britton, various other students of 
our trees have subsequently been unable to keep them apart as species. 
Thus, in 1918 Ashe recognized the extreme with short scales as B. 
lutea, var. alleghaniensis (Britton) Ashe,! and more recently I have 
so designated? much of the comon Yellow Birch of Nova Scotia. 
Subsequently, in an attempt to label properly the material in the 
Gray Herbarium and the herbarium of the New England Botanical 
Club, I have carefully studied the specimens, with the result that it 
seems possible to recognize two strong trends in the scales. The 
leaves do not show the difference indicated in the key-characters 
above quoted and, as already noted, Dr. Britton's own illustration 
of B. alleghaniensis shows no approach to cordate leaves. Neither 
does the difference of fruit brought out in his illustrations regularly 
accompany the differences in the scales. But in general the scales 
which are only 5-8 mm. long (I have been unable to find any mature 
scales as short as 4 mm. and the material in the Gray Herbarium of 
Biltmore Herb. no. 1619, the type-number of B. alleghaniensis, has 
the scales 7-8 mm. long) and with short (mostly 1-2 mm.) base are 
of firm or subcoriaceous texture; while the scales of the other extreme, 
1 Ashe, Bull. Charleston Mus. xiv. 11 (1918). 
? Fernald, Ruopora, xxiii. 257 (1922). 
