132 Rhodora [Jury 
where the branches spring; and this Fern is the Common Polypody. 
It is a Fern that delights to run along the ground amongst old wood 
and moss . . . It may justly be called a parasite—or rather an 
epiphytal plant—which seeks to hasten to destruction those trees 
where decay has made its appearance . . . A group of pollard 
willows clothed with Polypodium vulgare are [is] both singular and 
interesting." Similarly, the Pacifie American varieties of P. vulgare 
delight in mossy carpets, old stumps and tree-trunks. Thus Watson, 
in the Botany of California speaks of P. vulgare as “often growing 
on trees" and P. falcatum “On trees and sometimes on rocks"; 
Macoun & Burgess speak of P. falcatum as “frequent in the hollows 
of living trees"? Piper & Beattie assign P. occidentale to “moss on 
rocks, logs and trees"; * while Henry says of P. vulgare: * Often on 
mossy trees and logs ".^ 
How different from the ordinary habitat of Polypodium virginianum, 
which is accurately described in many books on the eastern American 
ferns. Thus Waters says that P. virginianum “prefers the top of a 
shaded ledge of rocks” ;* Miss Slosson likewise says: “Flat or slightly 
sloping surfaces of rocks, woodland banks, stone walls, etc." ; 7 while 
Clute equals Lowe in his vivid account: “ Wherever there is a shaded 
ledge of rocks in the northeastern States one is almost sure to find 
the polypody . . . There is no question as to choice of location 
with this sturdy species. All are alike to it, provided there are rocks 
upon which it can grow. "The only preference it has is for the tops 
and upper shelves of the rocks where the soil is moderately dry. 
So characteristic is it in such situations that when one sees a fern 
clad rocky summit from a distance too great to discern the individual 
fronds he identifies them with confidence as this species." * In fact 
so generally is P. virginianum of eastern America a plant of rock- 
habitats or woodland banks that, when it is rarely found as an epiphyte 
it at once attracts attention. Thus when the late Lester F. Ward, in 
1878, discovered it as an epiphyte on Betula nigra, he was so interested 
! Lowe, Our Native Ferns, i. 24, 25 (18067). 
? Watson, Bot. Cal. ii. 334 (1880). 
3 Macoun & Burgess, Trans, Roy. Soc. Can. ii. Sect. iv. 181 (1884). 
4Piper & Beattie, Fl. N. W. Coast, 3 (1915). 
¿ J. K. Henry, Fl. So. Brit. Columb. 3 (1915). 
$ Waters, Ferns, 79 (1903). ` 
7 Slosson, How Ferns Grow, 51 (1906). 
8 Clute, Our Ferns in their Haunts, 196 (1901). 
