126 Rhodora [JuLy 
completely lost them) and from this fact Linnaeus was misled into 
over-emphasizing this rather unusual and post-mortem character, 
describing his P. virginianum: “Polypodium frondibus pinnatifidis: 
pinnis oblongis subserratis obtusis, radice laevi" and adding the 
comparative note: " Antecedenti [P. vulgare] simillima, sed minor, & 
subtus glabra." This over-emphasis on the smooth rootstock was 
again displayed by Amos Eaton when, in 1818, he stated that P. 
vulgare, " var. virginianum, has a naked root," though Jacob Bigelow? 
had given a better description of the American plant and referred 
to the fronds as “divided . . . by sinuses which are more acute 
than in the European variety." 
The first post-Linnean botanist to make a really satisfactory 
differentiation of our plant from the European Polypodium vulgare 
was Sir William Hooker who, in 1840, considered typical P. vulgare 
almost strictly European, while in America there were two varieties: 
“B. Americanum; minus, fronde angustiore, laciniis remotioribus. 
P. Virginianum, Linn. Sp. Pl. p. 1345 (excl. Syn. Plum. &c.) 
Y. occidentale; frondis laciniis acutis acute serratis. P. vulgare, 
Virginianum. Bong. Veg. Sitcha, p. 57.’ Var. americanum was 
given a range through southern Canada west to the Saskatchewan 
and Slave River, while var. occidentale occurred from the mouth of 
the Columbia north to Sitka; and Hooker added under var. america- 
num the following illuminating comment: * The common state of this 
plant throughout the United States and in British N. America, is 
to be smaller than the European form, with narrower and more 
oblong fronds, with laciniae more distant, and the sori nearer the 
margin This is no doubt the P. Virginzanum of Linnaeus and authors, 
as far as regards the Virginia plant, on which Linnaeus founded his 
character." Somewhat later, in that storehouse of accurate obser- 
vation, his Flora of the State of New York, Torrey took up var. ameri- 
canum and in his description added the highly important character: 
“Segments mostly alternate, 3-4 lines wide."^ Still later, in 1848, 
Kunze, who certainly had an intimate knowledge of European ferns, 
published a suggestive comment: “P. vulgare, Q. americanum. 
Hook., (P. virginianum, L.,) differs from the European form by a 
1 Eaton, Man. ed. 2: 373 (1818). 
2 Bigelow, Fl. Bost. 252 (1814). 
3 Hook. Fl. Bor.-Am. ii. 258 (1840). 
4Torr. Fl. N. Y. ii. 484 (1843). 
