34 AMERICAN FERN JOURNAL 
a common origin. In the matter of scant variation 
two exceptions are noted in P. adiantiforme and P. 
triangulum. The former is a very widely distributed 
plant of both hemispheres, and the latter an inherently 
variable species of wide extremes in leaf proportion. 
The Polystichums of continental America offer greater 
difficulties, largely from lack of adequate material. 
The present paper deals with three forms ranging from 
Washington to Alaska. Two of these have been de- 
scribed by Mr. L. S. Hopkins as P. Andersoni and |g 
Jenningsi. The third, here characterized as new, 3s 
from Alaska. The three species differ among them- 
selves much less than the West Indian species; but 
the characters given below seem to be distinctive and, 
in the absence of intermediate plants, to justify their 
acceptance, temporarily at least, as full species. AS 
a group, they are nearest related apparently to P. 
Braunii, differing from that species in their simpler 
pinnae and more strongly aristate segments. 
close, linear-oblong, their apices acutish to long-acuminate; 
mostly auriculate or subauriculate, subsessile to semiadnat 
slightly or not at all decurrent. 1. Pa 
Fronds proliferous, 1 or 2 scaly buds invariably present 0 ne 
rachis 4-10 cm. from the apex of the lamina; pinnae mostly 
ascending, more remote, narrowly elongate-triangular, tape ne 
gradually from the base or near it, attenuate; segments ° 
lique, of an elliptical type and (excepting the basal ones) adnate 
or semiadnate, long-decurrent. the 
Lamina lance-elliptic, gradually reduced toward the base, © 1. 
basal pinnae about one-third as long as the middle ones; pee 
dle pinnae distinctly elongate-triangular from the base, * © 
2, P. Jennings 
ownward, 
he middle 
ones; middle pinnae much more slender, very 2 a 
angular, narrowed above the elongate basal segments, i 
8 times as long as broad at their middle. 3. P. Anderso"” 
