MAXON—STUDIES OF TROPICAL AMERICAN FERNS. 569 
Type in the U. S. National Herbarium, no. 464148, collected on moist moun- 
tain slopes near La Paz, Bolivia, altitude about 3,900 meters, March 18, 1906, 
by Dr. O. Buchtien (C. Baenitz, Herbarium Americanum, no. 1451) ; this num- 
ber is also well represented in the Gray Herbarium. A second collection of 
the same species is at hand from Pelichuco, Bolivia, altitude 3,300 meters, 
R. S. Williams 2637. 
As noted under P. pycnocarpum, the present species is the one mistakenly 
described by Kunze,’ upon Peruvian specimens collected by Cuming (no. 940), 
as P. macrocarpum, From P. pycnocarpum, which is perhaps its nearest ally, 
P. bryopodum differs materially in its lesser size, wide-creeping rhizomes, and 
more delicate, distant fronds, as well as in characters afforded by the scales 
of the rhizome and the under surface of the lamina. The two species are 
similar in having very narrow, subsecund rhizome scales, a feature which wholly 
excludes from comparison such plants as the Mexican P. fallacissimum and the 
Bolivian P. subvestitum, both here described as new. In the rhizome scales 
of none of these four species is there the sharp, strongly defined, blackish me- 
dian stripe which, with the wide, pale, repand border of thin-walled cells, un- 
mistakably characterizes the subgroup of P. plebejum and its several allies. 
12. Polypodium pycnocarpum C. Chr. Ind. Fil. 326. 1905. 
Polypodium macrocarpum Presl, Rel, Haenk, 1: 23, 1825, not Bory, 1810. 
TYPE LOCALITY: Mountains of Peru (Haenke). 
DISTRIBUTION : Mountains of Peru, altitude 3,700 meters. 
ILLUSTRATION: Presl, op. cit. pl. 1. f. 4 (as P. macrocarpum). 
This species as variously misunderstood in the past has included plants from 
a large part of continental America which pertain to several additional and 
entirely distinct species; for example, P. subvestitum, P. fallacissimum, P. 
tweedianum, and P. bryopodum. The affinities of these are indicated in the 
preceding key. True P. pycnocarpum is evidently very rare. The name pycno- 
carpum is merely a change made necessary by the circumstance that P. 
macrocarpum Presl is a homonym. 
The rather crude original illustration of this species by Presl was repub- 
lished by Kunze in 1840? in comparison with smaller Peruvian specimens 
(Cuming 940)* which were assumed to be of the same species and which formed 
the principal basis of a new description of supposed P. macrocarpum, as it was 
then called. That the figures of Haenke’s and Cuming’s specimens represent 
two species is now evident from exeellent Peruvian specimens lately received 
(Rose 19467), which agree very closely with Presl’s description and figure. 
The Cuming plants described and figured by Kunze are P. bryopodum, a new 
species here described. 
On the basis of Presl’s original description and illustration, but chiefly the 
Peruvian specimens of Dr. Rose’s recent collecting, P. pycnocarpum may be 
characterized as follows: 
Rhizome creeping, sparingly branched, 2 to 5 ecm. long, 1.5 to 2 mm. in 
diameter, freely radicose beneath, densely paleaceous, the scales imbricate, 
irregularly subsecund, about 3 mm. long, narrowly linear-deltoid (0.6 to 0.76 
mm. broad at the base), long-attenuate, dark brown in mass, somewhat bicol- 
orous by transmitted light, the dark median area composed of mostly linear- 
oblong, elongate-luminate cells with blackish sclerotic partition walls; marginal 
zone consisting of 2 or 3 rows of thin-walled whitish cells, the outermost trans- 
1Farrnkr. 1:25. pl. 13. f. 2a, c-g. 1840. 
2 Op. cit. 1: pl. 13. f. 2b. 
7 Op. cit. 1: pl. 13. f. 2a. c-g. 
