2 POLYPODIACEAE. 



Sori linear or oblong, at least twice as long as broad. 

 Sori marginal. 



Indusium present formed of the recurved leaf margin. 



Indusium double, the inner membranous one opening outwardly; leaves 



large, scattered. 7- Pteridiom. 



Indusium single. 



Leaves dimorphous, the sporophyls contracted and more or less pod- 

 like. 8. Cevptogramma. 

 Leaves uniform or nearly so. 



Leaves chaffy or tomentose, the ultimate segments small and bead- 

 like. 9. Cheilanthes. 

 Leaves smooth with dark polished stalks ; segments broader. 



10. Pellaea. 

 Indusium wanting; under surface (in the Colorado species) with white pow- 

 der; rachises zigzag. ii- Noetholaena. 

 Sori dorsal, oblique to the midribs or rachises, covered with a special in- 

 dusium. 

 Leaves pinnate or pinnately compound. 



Sori straight. 12. Aspleniom. 



Sori curved, often crossing the veins ; indusia occasionally horseshoe- 

 shaped. 13. Athyrium. 

 Leaves dichotomous, the divisions few and narrow ; small rock-loving plants 

 of the mountains. 14- Belvisia. 



I. POLYPODIUM L. Polypody. 



I. Polypodium hesperium Maxon. [P. vulgare of western botanists.] On 

 rocks, Mont, to B. C, Wash., Colo, and Ariz.— Alt. about 8500 ft.— Red Moun- 

 tain road, south of Ouray. 



2. PHEGOPTERIS Fee. Beech-Fern. 



I. Phegopteris Dryopteris (L.) Fee. In moist-rocky places; Newf. to 

 Alaska, Ore., Colo, and Va. — Alt. about 8000 ft. — Green Mountain Falls. 



3. POLYSTICHtJM Roth. Holly-Fern. 



I. Polystichum Lonchitis (L.) Roth. On rocks, Arctic America to N. S., 

 Calif, and Colo. — Alt. 8500-10,000 ft. — Ruby; Red Mountain road, south of 

 Ouray; Fish Creek Falls, Routt Co. 



4. DRYOPTERIS Adans. Male-Fern, Wood-Fern. 



I. Dryopteris Filix-mas (L.) Schott. On rocks, N. S. to northern Mich., 

 Alaska, Calif., Ariz, and Colo. — Alt. 6000-8500 ft. — Red Mountain road, south 

 of Ouray; Horsetooth Mountain; Canon City; Rist Canon. 



5. WOODSIA R. Br. 



Teeth of young leaves coarse, not ciliate. 



Stalks and pinnules covered with minute flattened hairs. i. W. scopulina. 



Stalks and pinnules smooth. 2. W. oregana. 



Teeth of young leaves fine, ciliate at the tips. 3. W. mexicana. 



I. Woodsia scopulina D. C. Eaton. On exposed rocks, Mich, to B. C, 

 Calif., Ariz, and Colo.— Alt. 5000-7000 ft— North Cheyenne Cafion; vicinity 

 of Arthur's Rock; Boulder; Horsetooth Gulch; gulch west of Soldier Canon; 

 foot-hills, Larimer Co. ; South Boulder Canon. 



