12 



POLYPODIACEAE. 



VOL. I. 



jagged lobes, or deeply stellate, the filiform divisions concealed beneath the sporanges or 

 inflexed and partially covering them. [Named in honor of Joseph Woods, 1776-1864, an 

 English architect and botanist] 



About 25 species, mainly of temperate or cold regions. Besides the following, another occurs 

 in the southwestern United States. Type species : Polypodium ilrense L. 



Indusium small or inconspicuous, the divisions narrow or filiform. 



Stipes jointed near the base; filiform divisions of the indusium more or less inflexed over 



the sporanges. 



Blades with more or less rusty chaff underneath. i. W. ilvensis. 



Blades glabrous or nearly so. 



Blades oblong-lanceolate ; divisions of the indusium numerous. 2. W. alpina. 



Blades linear or linear-lanceolate : divisions of the indusium few. 3. W. glabella. 



Stipes not jointed ; divisions of the indusium spreading, mostly concealed beneath the sporanges. 

 Puberulent, usually hispidulous ; indusium deeply cleft into narrow flaccid segments. 



4. W. scopnlina. 

 Glabrous ; indusium divided to the center into a few short whitish turgid beaded hair-like 



segments. 5. W. oregann. 



Indusium ample ; the divisions broad, early spreading. 6. W. obtusa. 



i. Woodsia ilvensis (L.) R. Br. Rusty Woodsia. Fig. 23. 



Acrostichum ilvense L. Sp. PI. 1071. 1753. 



Woodsia ilvensis R. Br. Prodr. Fl. Nov. Holl. i : 158. 1810. 



Rootstocks short, ascending, growing in masses, the 

 leaves closely caespitose. Stipes short, stoutish, jointed 

 near the base, rusty chaffy with narrow filiform scales; 

 blades lanceolate, 4'-io' long, pinnate, nearly glabrous 

 above, more or less covered with rusty chaff beneath ; 

 pinnae crowded, sessile, pinnately parted, the crowded 

 segments oblong, crenate ; sori borne near the margins 

 of the segments, somewhat confluent with age; indu- 

 sium minute, concealed beneath the sorus, cleft into 

 numerous filiform segments, these inflexed over the 

 sporanges and inconspicuous. 



On exposed rocks, Labrador to Alaska, south to North 

 Carolina, Kentucky and Iowa. Ascends to 5000 ft. in New 

 Hampshire. Also in Greenland. Europe and Asia. June- 

 Aug. Ray's Woodsia, Oblong Woodsia. 



2. Woodsia alpina (Bolton) S. F. Gray. Alpine Woodsia. Fig. 24. 



Acrostichum alpinum Bolton, Fil. Brit. 76. 1790. 

 Acrostichum hyperboreum Liljeb. Kgl. Vetensk. Akad. 



Nya Handl. 14: 201. 1793. 

 Woodsia hyperborea R. Br. Prodr. Fl. Nov. Holl. I : 



158. 1810. 

 W. alpina S. F. Gray, Nat. Arr. Brit. PI. 2: 17. 1821. 



Rootstocks short, ascending, the leaves densely 

 caespitose. Stipes slender, chestnut-colored, shining, 

 somewhat chaffy below, jointed near the base; blades 

 narrowly oblong-lanceolate, 2'-6' long, 8"-i2" wide, 

 scarcely narrower below the middle, deeply bipinna- 

 tifid ; pinnae somewhat apart, cordate-ovate or trian- 

 gular-ovate, pinnately 5-7-lobed, glabrous or very 

 nearly so on both surfaces; sori near the margin, 

 usually distinct ; indusium as in the preceding species. 



On moist rocks, Labrador to Alaska, Maine, northern 

 New York and western Ontario. Also in Greenland. 

 Ascends to 4200 ft. in Vermont. July-Aug. Called 

 also Northern Woodsia, Flower-cup-fern. 



