18 POLYPODIACEAE (FERN FAMILY) 



2. POLYPODIACEAE R. Br. FERN FAMILY 



Leafy plants; the leaves (fronds) often much branched, circinate in verna- 

 tion, rising from a rootstock. Spores of one kind, borne on the under surface 

 or margins of the leaves in sporangia (with an elastic ring), which are de- 

 veloped from a single epidermal cell. Prothallia above ground, green. The 

 sporangia are usually collected in little masses (fruit dots or sori), which are 

 'often covered by a scale (indusium), which is produced by a cellular ougrowth 

 from the frond, or by a general involucre formed from the infolded margin of 

 the frond. Eaton, Ferns of North America. 



Leaves of two kinds; the sterile broader than the fertile . . . 1. Cryptogramma. 

 Leaves all alike. 



Indusium wholly wanting. 

 Sori dorsal, roundish. 



Leaves 2-3-pinnatifid ........ 2. Phegopteris. 



Leaves simply pinnate . . . . . . . .3. Polypodium. 



Sori marginal, elongated 4. Notholaena. 



Indusium present. 



Formed from the inflexed leaf-margin. 



Sporangia on the underside of the reflexed portion of the leaf . 5. Adiantum. 

 Sporangia in a continuous vein-like groove, or receptacle, 

 which connects the ends of the veins. 



Large plants of moist copses 6. Pteridium. 



Small plants of cliffs and rock slides. 



Pinnae tomentose or scaly beneath . . . . . 7. / Cheilanthes. 



Pinnae smooth beneath 8. ' Pellaea. 



Formed from epidermal cells (not from the leaf-margin) and 



variously attached. 

 Sori round. 



Indusium superior, reniform or peltate, attached by a 



central stalk. 

 Sori near the midvein of the leaf ..... 9. Dryopteris. 



Sori near the margin of the leaf 10. Polystichum. 



Indusium inferior or partly so. 



Hood-like, attached to the inner side, soon open on the other 1 1 . Filix. 

 Cup-like, attached underneath, bursting above into a 



fimbriated margin . . . . . . .12. Woodsia. 



Sori oblong or linear . . . . . . .13. Asplenium. 



1. CRYPTOGRAMMA R. Br. ROCK BRAKE 



Rootstocks short, bearing numerous light-green small smooth fronds of two 

 kinds; the sterile much broader than the taller fertile ones; all with stramineous 

 stipes. Sori extending down the free veins. Involucre very broad, at length 

 flattened out and exposing the now confluent sori. 



Stipes tufted; fronds 3-4-pinnate . . . . . . .1. C. acrostichoides. 



Stipes scattered; fronds 2-3-pinnate . ' 2. C. Stelleri. 



1. Cryptogramma acrostichoides R. Br. App. Frank, Journ. 767. 1823. 

 Fronds 5-10 cm. long, chartaceous, ovate, closely 3-4-pinnate; pinules ovate 

 or obovate, adnate-decurrent, those of the fertile fronds narrower and longer, 

 the involucres very broad: sori extending far down the veinlets. In dense 

 patches among rocks; California to Colorado, thence far northward and east 

 to Lake Superior. 



2. Cryptogramma Stelleri (Cm.) Prantl, Engler's Bot. Jahrb. 3: 413. 1882. 

 Rootstock very slender, creeping, nearly naked: fronds very delicate, 5-10 cm. 

 long, oblong-ovate, pinnate with a few once or twice pinnatifid pinnae; seg- 

 ments oblong or obovate; involucres broad and delicate. Pellaea gracilis. 

 Crevices of damp and shaded limestone rocks; Colorado, northward and east- 

 ward to Labrador, and thence south to Pennsylvania. 



2. PHEGOPTERIS Fee 



Medium sized ferns with leaves 2-3-pinnate, triangular-ternate, the primary 

 divisions stalked and the rachis not winged. Sori small, on the back of the 

 veins below their attenuate apices. Indusium wholly wanting. 



