10 46 POLYPODIACEAE 



2 A viride Huds. Fronds tufted; blades 2.7-20 cm. long, 0.8-1.5 cm. 

 broad linear-lanceolate; pinnae roundish ovate or rhombic, obtuse, broadly 

 cuneate at base, the lower side obliquely truncate; margins, excepting the basal 

 parts, deeply crenate; sori near the margins; indusia entire or denticulate On 

 rocks: Newf.-Vt.-Sask.-(Black Hills) S.D. Wyo. Wash.-Alaska. Mont. 



3 A Trichomanes L. Fronds tufted; blades 4-18 cm. long, linear; rachis 

 faintly alate not fibrillose; pinnae mostly oval or oval-oblong, inequilateral; 

 margins, except the basal sides, slightly crenate; veins on both sides of the mid- 

 veins usually forked; indusia commonly slightly crenulate. On rocks: Hudson 

 Bay Ala. Ariz Alaska; Eu., the Azores, and Canary Islands. Submont. 

 Mont. 



4. A. platyneuron (L.) Oakes. Fronds tufted, the fertile erect, 20-50 cm. 

 long'2.5*-6.3 cm. broad, the sterile rosulate much shorter; blades linear-oblanceo- 

 late,' gradually reduced toward the base; pinnae auriculate-lanceolate, subfalcate, 

 crenate, serrate, or incised, the lower oblong or deltoid; sori oblique, near the mid- 

 veins. Among rocks or stones: s Ont. Me. Fla. N.M. Colo.; Africa. Sub- 

 mont. Mont. 



6. A. Adiantum-nigrum L. Fronds tufted; stipes and lower part of the 

 rachis chestnut-brown, except in young plants; rachis winged; blades 3-33 cm. long, 

 ovate-deltoid to elongate-deltoid; lower pinnae deltoid, or nearly so, those above 

 mostly lanceolate-deltoid, gradually passing into the pinnatifid apex of the 

 blade; segments ovate to spatulate, cuneate at base, sharply toothed or ob- 

 liquely cleft into toothed lobes; veins very oblique; indusia entire or subentire. 

 A. Andrewsii A. Nels. On rocks: Colo.; Eurasia, and Africa. Submont. 



9. ATHYRIUM Roth. LADY FERN. 



Various sized ferns, with more or less compound fronds. Scales of the rhizome 

 with thin-walled cells. Veins free. Sori borne on the veins, indusiate, mostly 

 oblong or linear-oblong and curved at one end over the vein, or bent back upon 

 itself along the other side of the vein, often horseshoe-shaped, occasionally round- 

 ish. Indusia following the shape of the sorus, attached along its length at the 

 side next the vein, opening outwardly, rarely vestigial and hidden. 



Pinnules commonly somewhat cuneate at base, sometimes appearing short-stalked; in- 

 dusia rarely seen, very minute and evanescent. 1. A. alpestre. 

 Pinnules more or less parallel at base down to the rachis, at least on the upper side ; 



indusia evident. 

 Indusia straight or variously curved, often shaped like a shepherd's crook. 



2. A. filix-foemlna. 

 Indusia mostly curved so as to appear circular with a narrow sinus. 3. A. cyclosorum. 



1. A. alpestre (Hoppe) Rylands. Rhizome short, stout; fronds in a crown, 

 25-95 cm. long; blades oblong-lanceolate, slightly narrowed toward the base, bi- 

 or tripinnate; pinnae deltoid-lanceolate, their rachises commonly very narrowly 

 winged; pinnules ovate-oblong or oblong-lanceolate or deltoid-lanceolate, some- 

 what obliquely incised or pinnatifid or occasionally pinnate below; segments 

 sharply toothed. Alaska Mont. Colo. Calif.; Que.; Eu. 



2. A. Filix-foemina (L.) Roth. Rhizome short, creeping; fponds closely 

 clustered, 1.3-12.5 dm. long; stipes straw-colored, brownish or pinkish red; 

 blades firmly herbaceous to herbaceous-membranous, rather deep green, often 

 with a bluish tinge, except when growing in sun, broadly oblong-ovate to oblong- 

 lanceolate or broadly lanceolate, not or somewhat shortly narrowed at base; 

 pinnae short-stalked or the upper sessile, lanceolate, acuminate, toward apex 

 pinnatifid, below pinnate or nearly so; pinnules oblong-lanceolate or broadly 

 elliptical, incised or serrate, the lobes or teeth often again toothed; sori oblong, 

 linear or hamate or occasionally horseshoe-shaped; indusia subentire to ciliate, 

 the cilia often jointed and occasionally gland-tipped; some at least of the spor- 

 angia with a flat, jointed gland-tipped hair on the pedicel. Woods and fields: 

 Ont. Newf. Fla. La.; Tex. Ariz.; (Black Hills) S.D.; the Old World. 

 Probably also extends farther north in Canada. 



