FERN FAMILY 281 



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

 tions of the margins of tlie frond. 

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



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 rliizome. 15. Polypodium. 



Stipes not jointed to the rhizome. 6. Thei.ypteris. 



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



Sori borne on the under side of refle.xed lobes of the frond. 10. Adi.\xtum. 

 Sori not borne on the under side of tlie refle.xed portions of the margin of the 

 frond. 

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



veinlets. 11. Pteris. 



Sori borne on the veins at or near their tips. 



Sori e.xtending down the veins; edges of the fertile fronds Anally open- 

 ing out flat; sterile and fertile fronds markedly dissimilar. 



12. Ckyptogramma 

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

 what dissimilar. 

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



glabrous or nearly so. 13. Pellaea. 



Sori distinct or contiguous; seamenis usually pubescent, tomentose 

 or scaly. " 14. Cheilanthes. 



1. ONOCLEA L. SEX.SITIVE Ferx. i. O. sensibilus. 



2. PTERETIS Raf. Ostrich Fern. 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 tlie indusia or segments, glabrous 



or minutely glandular. 

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



3. W. oregana. 

 Indusia 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. meiicana. 



Lobes of indusia merely jagged, rarely with an occasional jointed extension, 

 often glandular. 5. W. oblusa. 



4. FILIX Adans. 



Blades of the fronds deltoid-lanceolate or broadly lanceolate, twice or thrice pinnate. 

 Blades elongate deltoid-lanceolate, 3-12 dm. long; basal pair of pinnae tlie 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, tliree to four times pinnate. 3. F. inontana. 



5. POLYSTICHUM Roth. Holly Fern, Christmas Fern. 



Blades normaUy simply pinnate; pinnae auricled or the upper side at base, obhquely 

 truncate at tlie lower. 

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



1. P. loncltitis. 

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

 linear, acuminate. 2. P. munilum. 



Blades normally more compound. 



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



Blades not proliferous. 



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



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 onl3- the basal pair of pinnae slightly shortened. 



1. T. Phegopleris. 

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



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



Fronds glabrous, e.xcepting a few scales on the stipe, or with only occasional micro- 

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

 Fronds distmctly 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. 



