542 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
POLYPODIUM TRICHOMANOIDES AND ITS AMERICAN ALLIES. 
The name Polypodium trichomanoides, given by Swartz in 1788 to 
a common plant of the Blue Mountains of Jamaica, was often ap- 
pled very loosely by later writers and, although various related 
forms were described as valid species from time to time, the char- 
acters of these were not well understood, and there was little attempt 
to correlate them until the appearance in 1905 of an excellent paper 
by Hieronymus upon several groups of Polypodium.' To this au- 
thor is due the credit of establishing the relationship and distinctive 
characters of a majority of the species in the group, as defined by 
him, and of demonstrating the usefulness and value of the minute 
but obvious structural differences of the rhizome scales. These 
characters, which are constant, can mostly be made out by means of 
a hand lens, although for greater accuracy and for the sake of 
repeated observation it is far preferable to preserve the scales as 
permanent microscopic mounts. 
In the present paper, which is to a certain extent supplementary to 
that of Hieronymus, the group of P. trichomanoides is somewhat 
enlarged in scope, and several of Jenman’s species which were over- 
looked or omitted by Mieronymus are also included, as well as others 
which have since been described by Christ, Rosenstock, Hieronymus, 
and the writer. Brief critical notes upon these are given in the 
following pages. 
Strictly delimited, the group should include only those species 
which have the general facies and particularly the long-setose vesti- 
ture of P. trichomanoides, the principal characters of the plants be- 
ing a smallish ascending or erect rhizome, with fulvous to reddish 
brown, ciliate or toothed rhizome scales, the few fronds mostly 3 to 
15 cm. long, short-stipitate, slender, the lamina linear to narrowly 
linear-lanceolate, pinnately lobed to pinnatisect, the lobes or seg- 
ments with a simple or once-forked vein, and invariably monosorous,? 
both the stipe and the lamina (especially upon the under side) being 
clothed with numerous long, spreading, stiffish, reddish hairs. Thus 
defined, the group would not include P. micropteris, P. limula, P. 
harti, and P. nutatum, which have entire rhizome scales and fronds 
at most subsetulose, never long-setose. It would also exclude 
P. grisebachii, P. perpusillum, P. mitchellae, P. shaferi, P. schenckii, 
and P. erganense, plants whose fronds range from subglabrous to 
pubescent, but are never long-setose with reddish hairs. All of these, 
however, have the small stature and monosorous lobes or segments of 
P. trichomanoides and its more immediate relatives and may there- 
fore be included in this group. The first four mentioned above 
*Hedwigia 44: 78-105, 1905. 
* See, however, under P. blepharolepis (page 556). 
