The Ferns of Washington 101 



triangular, thinly herbaceous; its main divisions short- 

 stalked, 1 -2-pinnate; ultimate segments toothed. Spore- 

 leaf 2- 3-pinnate. — British Columbia to Labrador, south 

 to Washington, Arizona, Texas, Florida. 



6. Botrychium silaifolium Presl. (PL 6, /. 7.) 



Plant robust, 15-24 inches high. Foliage-leaf large, 

 usually broader than long, with petiole 3-8 inches long, 

 its 3 main divisions 2 -3-pinnate; ultimate segments 

 lobed, crenulate. Spore-leaf long-petioled, usually 

 overtopping the foliage-leaf, 2 -3-pinnate. — British Co- 

 lumbia and Washington. 



POLYPODIACEAE. True Fern Family. 



Plants terrestrial, perennial, evergreen or not. Leaves 

 (fronds) growing from a rhizome in tufts or singly, 

 1-3 times divided into leaflets (pinnules) or lobes, 

 coiled at tips when young, unrolling and growing at 

 apex until mature. In most genera all the leaves are 

 alike, other genera have distinct foliage- and spore-leaves. 

 Spores very abundant, all alike, borne on backs of 

 unmodified foliage-leaves or these somewhat modified 

 but green, in sporangia which occur in groups (sori); 

 sori may or may not be covered each by an indusium 

 consisting either of a separate membrane or the in- 

 rolled edge of the leaf. Thalli small, green, somewhat 

 heart-shaped, on soil or decaying wood. 



Key to the Genera — Based on the Leaves 



(See also p. 103) 



A. Leaves pinnately compound, their main divisions not 2 or 3. 



B. Leaves once pinnate or pinnately deep-lobed, tufted or scattered 



C. Leaflets entire to serrate. 



D. Blades of the leaflets not narrowed to their midribs at b 

 E. Leaves not tufted, all alike; rootstocks creeping. 



16. POLYPODIUM. 



EE. Leaves tufted, of 2 kinds; rootstocks not creeping. 



8. LOMARIA. 



DD. Blades of the leaflets narrowed to their midribs at base. 



