The Ferns of Washington 51 



side of its branches; leaflets delicately stalked, 1-sided. 

 ■In damp shady places. Alaska to Quebec, south to 

 California. 



15. PTERIDIUM. Brake. 



Leaves not tufted; blade 1-3-pinnate (3 in ours), 

 large. Sori marginal, continuous, under the inrolled 

 leaf-margin, on a marginal vein which connects the ends 

 of the lateral veins. (Greek pterm** wing, hence also 

 Greek pteris = st fern, because feather-like leaves are 

 common in the group though not in this genus.)— The 

 rootstocks were roasted and pounded, giving a flour 

 used by the northwest Indians. The young shoots are 

 eaten like asparagus by the French and Japanese. A 

 bad weed in western Washington and Oregon. We 

 have only the following species. 



1. Pteridh u aouilinum pubescens Underw. (Plate 



18, f. 3, 4. Plate 19.) 



Common Brake. 

 Rootstock stout, creeping, underground. Leaves 1- 

 14 feet high, erect, covered with fine silky hairs especi- 

 ally beneath; petiole woody; blade triangular, ln- 

 dusium double, outer formed of the incurved margin 

 of leaf, inner attached within the receptacle and ex- 

 tending beneath the young sporangia.— The most com- 

 mon of our ferns.— Alaska to California and Arizona. 



16. POLYPODIUM. Polypod. 



Rootstock creeping, elongated; petioles articulated to 

 slightly prominent knobs on scaly rootstocks; blade 

 1-pinnately divided. Sori round, large, naked, on tips 

 of veins, one row on either side of mid-vein (Greek 

 poly = many, pons - foot, referring to the branched 



rootstock.) 



