POLYPODIUM VULGARE AS AN EPIPHYTE! 
DuNCAN S. JOHNSON 
(WITH THREE FIGURES) 
While Polypodium vulgare is common on rocks, may often grow 
on the trunks of fallen trees, or sometimes even creep a few feet 
up living trunks, Ihave not been able to/ffind a definite report of 
its being really epiphytic in habit in the United States. ScHIMPER,’ 
the first general student of. American epiphytes or air plants, says 
(1888, p. 131): 
In the North American forests’ the shade plants of the soil would not be 
able, because of lack of moisture, to grow on. the bark of trees. Thus the so 
common Polypodium vulgare ascends to the trees in North America, just as 
little as it does in central or northern Europe. 
Observations made:at Cockeysville near Baltimore, Maryland, 
latitude 39° 30’ N, shows that this polypody can grow-and fruit 
for years as.a true epiphyte, high up on'the erect branchless trunks 
of living trees. The ferns were not growing in an unusually moist 
region, as was true of the epiphytic individuals of it reported by 
Curist’ (p. 325) as growing near.a waterfall as. Montreux, or in 
the damp forests of Portugal (see also ScHIMPER 1888, p. 31). 
On ‘the contrary, the trees bearing this fern in Maryland were 
near the top of’a northward facing cliff, more than 100 feet above 
a small stream, and at the western end of a ravine which is about 
125 yards wide at this level. Two dozen or more plants of this 
fern were found growing in the deep furrowed bark of six different 
chestnut‘ oaks (Quercus Prinus). |The clumps of polypody were at 
various heights’ up to 20 feet or more above the ground. Clumps 
of all sizes were found, showing that they had started on the tree 
from prothallia, and had not:arisen from rhizomes that had climbed 
upward from'the soil. With one exception they were all on the 
north side (between N.N.E. and N.N.W.) of single erect trunks. 
* Botanical contribution from the Johns Hopkins University, no. 70. 
?Scummperr, A. F. W., Die epiphytische vegetation Amerikas. 1888. 
3 Curist, H., Geographie der Farne. 1910. 
237) : [Botanical Gazette, vol. 72 
