1. Woodsia Ilvénsis (L.) R. Br. Rusty Woodsia. (Fig. 16.) 
Acrostichum Ilvense 1, Sp. Pl. 1071. 1753. 
Was Iilvensis R. Br, Trans. Linn. Soc. 1%: 173. 
IS12. 
Rootstock short, caespitose. Leaves lanceolate, 4/— 
10’ long, pinnate, glabrous above, more or less covered 
with rusty chaff beneath, as are also the slender stipes; 
pinnae crowded, sessile, pinnately parted, the crowded 
segments oblong, obscurely crenate; stipes jointed 
near the base; sori borne near the margins of the | 
seginents, somewhat confluent when old; indusium 
minute, concealed beneath the sorus, its margin cleft 
into filiform segments which are inflexed over the 
sporanges and inconspicuous, especially when the 
latter have scattered their spores. ; 
10 POLYPODIACEAE. 
On exposed rocks, Labrador and Greenland to the | 
Northwest Territory, south to North Carolina and Ken- 
tucky. Ascends to 5000 ft. in New Hampshire. Also in 
Europe and Asia. June-Aug. 
2. Woodsia alpina (Bolton) S. F. Gray. 
Alpine Woodsia. (Fig. 17.) 
Acrostichum alpinum Bolton, Fil. Brit. 76. 1790. 
Acrostichum hyperboreum JVljeb. Act. Stockh. 201. 
1793- 
Woodsia hyperborea R. Br. Trans. Linn. Soc. 11: 173. 
1812. 
Woodsia alpina §. F. Gray, Nat. Arr. Brit. Pl. 2: 17. 
1821. 
Rootstock short, caespitose. Leaves narrowly ob- 
long-lanceolate, 2/-6’ long, 8//—12’’ wide, scarcely 
narrower below the middle; pinnae cordate-ovate 
or triangular-ovate, pinnately 5-7-lobed, glabrous 
or very nearly so on both surfaces; stipes jointed 
near the base; sori somewhat scattered on the seg- 
ments ; indusium as in the preceding species. 
On moist rocks, Labrador to Alaska, south to Maine, 
northern New York and western Ontario. Ascends to 
4200 ft. in Vermont. July—Aug. 
3. Woodsia glabélla R. Br. Smooth 
Woodsia. (Fig. 18). 
Woodsia glabella R. Br. App. Franklin’s Journ. 754. 
1823. 
Rootstock small, caespitose. Stipes obscurely 
jointed at the base ; leaves linear or narrowly lan- 
ceolate, 2/-5’ long, 4’’ 8’’ wile ; pinnae deltoid to 
ovate, the lower remote, obtuse, crenately lobed, 
often somewhat smaller than the middle ones, 
glabrous or nearly so; sori scattered on the seg- 
ments; indusium minute, membranous, with 6-10 
radiating segments, covered by the sporanges, its 
filamentous segments only inflexed over them 
when young as in the two preceding species. 
On moist rocks, Labrador to Alaska, south to New 
Humpshire, Vermont, northern New York and the 
north shore of Lake Superior. Also in arctic and 
alpine Europe and Asia. Summer. 
