FERN FAMILY 281 



Sori naked, or protected, at least at first, by the revolute or reflexed margins or Dor- 

 tions of the margins of the fi-ond. 

 Margin of the frond flat or merely revolute, not modifled. 



Margin of the frond revolute; sori more or less confluent, forming a marginal 



band. 16. Notholaena. 



Margin of the frond flat; sori dot-like on the veins. 



Stipes jointed to the riilzome. 15. Polypodium. 



Stipes not jointed to the rhizome. 6. Thelypteris. 



Margin of the frond reflexed over the sori, more or less modifled. 



Soriborneontheundersideof reflexed lobes of the frond. 10. Adiantum. 

 Sori not borne on the under side of the refle.'ced portions of the margin of the 

 frond. 

 Sori borne on a continuous vein-like receptacle connecting the ends of the 



velnlets. 11. Pteris. 



Sori borne on the veins at or near their tips. 



Sori extending down the veins; edges of the fertile fronds finally open- 

 ing out flat; sterile and fertile fronds markedly dissimilar. 



12. Crypiogramma. 

 Sori marginal or submarginal; sterile and fertile fronds aUke or some- 

 what dissimilar. 

 Sori confluent, forming a submarginal band ; segments of the fronds 



glabrous or nearly so. 13. Pellae.\. 



Sori distinct or contiguous; segments usually pubescent, tomentose 

 or scaly. 14. Cheil.\nthes. 



1. ONOCLEA L. Sensitive Fern, l. O. sensibilus. 



2. PTERETIS Raf. Ostrich Fbkn. i. P. nodulosa. 



3. WOODSIA R. Br. 



- Stipe articulate near the base. 1. W. glabella. 



Stipe not articulate. 



Blades pulverulent, with flattened articulate hairs and stalked glands. 



2. W. scopulina. 

 Blades without articulate hairs, unless at the ends of the indusia or segments, glabrous 



or minutely glandular. 

 Indusia very small, divided almost to the center into a few hair-Uke filaments. 



3. W. oregana. 

 Tndusia large, cleft more or less deeply into several lobes. 



Lobes of the indusia divided at least halfway down into slender articulate 

 flattened hairs. 4. W. mexicana. 



Lobes of indu.sia merely jagged, rarely with an occasional jointed extension, 

 often glandular. 5. W. obtusa. 



4. FILIX Adans. 



Blades of the fronds deltoid-lanceolate or broadly lanceolate, twice or tlu'ice pinnate. 

 Blades elongate deltoid-lanceolate, 3-12 dm. long; basal pair of pinnae the largest. 



1. F. bulbifera. 

 Blades broadly lanceolate, 2-4.5 dm. long; basal pair of pinnae usually slightly short- 

 ened. 2. F. fragilis. 

 Blades of the fronds deltoid-ovate, three to four times pinnate. 3. F. montana. 



5. POLYSTICHUM Roth. Holly Fern, Christmas Fern. 



Blades normally simply pinnate; pinnae auricled or the upper .side at base, obliquely 

 truncate at the lower. 

 Fronds very short-stalked ; pinnae broadly lanceolate, falcate, on the lower triangular. 



1. P. lonchitis. 

 Fronds rarely very short-stalked; pinnae horizontal, slightly falcate, lanceolate or 

 linear, acuminate. 2. P. munitum. 



Blades normally more compound. 



Blades proliferous below the apex. 3. P. Andersoni. 



Blades not proliferous. 



Pinnae serrate in the distal part, pinnately lobed at base. 4. P. scopulinum. 



Pinnae pinnately divided almost -throughout the blade, commonly fully bipinnate. 



5. P. Braunii. 



6. THELYPTERIS Schmidel. 



Blades of the fronds bipinnatifld. 



Blades broadest at base, or only the basal pair of pinnae slightly shortened. 



1. T. Phegopteris. 

 Blades gradually much narrowed toward base. 2. T. Oreopteris. 



Blades of the fronds ternate or subternate, once to twice pinnate. 



Fronds glabrous, excepting a few scales on the stipe, or with only occasional micro- 

 scopic trichomes resembling rudimentary glands. 3. T. Dryopleris. 

 Fronds distinctly glandular, especially the stipes and rachises; glands capitate. 



4. T. Robertiana. 



7. DRYOPTERIS Adans. Shield Fern, Male Fern. 

 Indusia comparatively large, not dot-like. 



Sori not close to the margin. 



