1922] Fernald,—Polypodium virginianum and P. vulgare 127 
narrower and more elongated frond, narrower lobes separated by 
wider sinus, the lowest being longer or at least not shorter than the 
following ones, and the sori being always nearer the margin than in 
the European plant. I have not met with any American specimens 
entirely agreeing with the true P. vulgare of the old world." 
These quotations are sufficient to indicate that the most discerning 
of the earlier students of our ferns were convinced that no true 
Polypodium vulgare occurs in eastern. America, although there was 
difference of judgment as to whether our plant was specifically or 
only varietally separable from it. Since the statements above 
quoted little has been consciously added to the once rapidly accumu- 
lating series of differential characters and for three-fourths of a 
century our plant has passed, with only desultory and inconclusive 
challenges, as typical P. vulgare. For instance, the late B. D. Gilbert 
stated that, “For some time past I have been inclined to look upon 
our so-called Polypodium vulgare in Eastern North America as a 
distinct species from the European and Pacific coast species... 
However, I am not yet prepared to separate the two, which can only 
be done by one who has a large number of European as well as 
American specimens;’’ while the English specialist, the late C. T. 
Druery, in 1902, assumed the identity of P. virginianum with European 
P. vulgare when he urged “The undesirability of attaching different 
names on your [American] side to varietal types which may already 
exist on this [European]. ? In 1907, it is true, Tidestrom took up 
our plant as P. virginianum, but with only one highly inconstant 
cliaracter: “In its outward appearance this species differs in no 
appreciable degree from P. vulgare. The latter species is characterized 
by having from 3 to 5 stelai at the base of the petiole, while in our 
plant the number is commonly 2, and inolderleaves3,—2 being normal 
and 1 is smaller."* In such a discriminating work as Christensen’s 
Index Filicum, however, P. virginianum appears as an unquestioned 
synonym of P. vulgare, although full specific rank is accorded P. 
californicum Kaul., P. falcatum Kell. (P. vulgare, var. occidentale 
Hook., P. Glycyrrhiza D. C. Eaton, P. occidentale (Hook.) Maxon) 
and P. hesperium Maxon, plants so strongly resembling variants 
! Kunze, Am. Journ. Sci. ser. 2, vi. 82 (1848). 
? Gilbert, Fern Bull. x. 14 (1902). 
3 Druery, Fern Bull. x. 51 (1902). 
1 Tidestrom, Elysium Marianum, ed. 2: 18 (1907) 
