104 American Fern Journal 



I. Indusium over sori. 



J. Petioles more or less scaly; indusium conspicuous. 



K. Indusium round, peltate; leaf-blades linear to lanceolate, 



tOllgh. 5. POLYSTICHUM. 



KK. Indusium cordate; leaf-blades obovate or oblanceolate 

 with narrow base, or oblong or ovate with wide base, 

 membranous. 4. Dryopteris. 



JJ. Petioles not scaly; indusium inconspicuous, hood-like; 



leaf-blade delicate, oblong to lanceolate. 



2. Cystopteris. 



II. Indusium under sori; sori stellately divided; small tufted 

 ferns growing on rocks; petioles coarse, woody. 



1. Woodsia. 

 HH. Sori not round. 



L. Sori oblong or linear; leaves all alike, pinnately divided. 

 M. Sori oblique to mid-vein, separate, not in depressions; 



leaves small. 7. Asplenium. 



MM. Sori parallel to mid-vein in chain-like rows in depressions; 

 leaves large. 9. Woodwardia. 



LL. Sori continuous in band next to midrib; leaves of two kinds, 



pinnately divided. 8. Lomaria. 



LLL. Sori curved, more or less circular; leaves all alike, bipinnate, 

 narrowly ovate, narrow at base. 6. Athyrium. 

 AA. Indusium none, sori naked. 



N. Sori elongated, spreading, following the veins; leaves triangular, 

 2-3-pinnate; lower surface covered with yellow to white powder. 



10. Ceropteris. 

 NN. Sori round or elliptical, leaf-back not covered with powder. 

 O. Sori large, on tips of veins; leaves pinnately divided; petiole 

 jointed to root, stock. 16. Polypodhjm. 



P. Leaf-blade triangular in general form and leaflets acute. 



3. Phegopteris. 



PP. Leaf-blade either not triangular in general form, or if so the 

 leaflets rounded and quite blunt. 16. Polypodium. 

 OO. Sori small, on backs of veins below apex; leaves ternate or 

 2-3-pinnate; petiole not jointed to rootstock. 



3. Phegopteris. 



1. WOODSIA. 



* 



Small tufted ferns growing mostly upon rocks; 

 petioles coarse, woody; leaf-blades 2-pinnate. Indusium 

 under the round sorus, stellately divided into lobes or 

 fringes. (Honor of J. Woods, an English botanist.) 



A. Leaf-blades smooth; leaflets or lobes 4-6 pairs on each primary 



leaf-division; lobes of indusium hair-like. 1. W. oregana. 



AA. Leaf-blades hairy; leaflets or lobes fi 12 pairs on each primary 

 leaf -division; lobes of indusium widest at base. 2. W. scopulina. 



1. Woodsia oregana Eat. (PL 6, f. 1, 2.) 



Leafy in appearance. Petiole equal in length to 

 blade; leaf-blade smooth, lanceolate, partly 2-pinnate, 



