1922] ` Fernald,—Polypodium virginianum and P. vulgare 131 
authors when describing their plant, for example Luerssen who 
definitely calls the scales "schildfórmig."! Careful comparison of 
scales from the two plants shows this to be a constant character and, 
as would be expected, the scales of the western American P. californi- 
cum, P. falcatum and P. hesperium agree with the European P. 
vulgare in being peltately attached just above their base. 
Reference has been made to Tidestrom's statement that P. virginia- 
num differs from P. vulgare in having only 2 or 3 vascular bundles at 
the base of the stipe, two of them large, the third smaller; while in 
P. vulgare there are said to be 3 to 5 bundles. Luerssen? somewhat 
similarly describes P. vulgare as having at the base of the stipe 2 
large and 2 smaller bundles, while Waters? definitely places our plant 
in his section with “ Bundles three at extreme base." Whether there 
is any pronounced difference in the number and arrangement of the 
bundles cannot be determined without more adequate European 
material; but it is significant that some dried European plants, in 
which the stipe has been severed just above the base, seem to show 
only 2 bundles while others show but 3. 
The habitats of Polypodium vulgare and of P. virginianum are 
usually very different. Although some forms occur on rocks or on 
mossy banks or even sand dunes,‘ a common habitat in Europe is 
tree-trunks (either living or dead), old stumps and fallen logs. The 
early European herbalists, for instance Gerarde in the 16th century, 
distinguished “ Polypodium Quercinum Polipodie of the Oke,” which 
occurs “in the tops of the trunks of trees in thicke woods”’;> Kerner 
von Marilaun in his popular compilation, the Natural History of 
Plants (Pflanzenleben), says: “ Polypodium vulgare is often met with 
enveloping the trunks and boughs of large trees" ;* Luerssen briefly 
states its habitat in continental Europe: “Auf Baumwurzeln und 
Baumstumpfen, moosbewachsenen Felsblocken, an alten Mauern 
und in Felsspalten";? while Lowe gives the following vivid picture 
from Great Britian: “Looking higher up the tree, an epiphyte in the 
shape of a Fern has taken possession, and is clothing the forks from 
1 Luerssen, Farnpfl. 54 (1889). 
2 Luerssen, Farnpfl. 55 (1889). 
3 Waters, Ferns, 73 (1903). 
4Warming, Oecology of Plants, ed. Groom & Balfour, 267 (1909). 
5 Gerarde, Herball, 974 (1597). 
$ Kerner von Marilaun, Nat. Hist. Pl. ed. Oliver, ii. 705 (1895). 
T Luerssen, Farnpfl. 55 (1889). 
