72 Maidenhair Spleen wort 



the uppermost sessile, articulated at points of attachment; the 

 lower reduced, roundish-oblong or roundish-oval or reniform, 

 or roimdish-fan-shaped with cuneate or truncate base; those 

 above roundish-oblong or oval, obliquely wedge-truncate at base, 

 inasquilateral, sometimes auricled on upper side; except at base 

 somewhat crenate or sometimes more or less incised: surfaces 

 glabrous: rachis purplish-brown, glossy, flattened or slightly 

 convex on face, appearing furrowed from wings connecting 

 pinnae which are similar to and continuous with wings of petiole : 

 foot-stalks of pinnae purpHsh-brown : color otherwise deep green: 

 texture firmly membranaceous. 



Venation pinnate, free: primary branches of pinnae's mid- 

 veins, excepting the basal, mostly once-forked or the outermost 

 simple, or a few bearing branches which are simple to twice 

 forked: superior or both basal primary branches of midveins 

 once to three times forked or bearing branches which are simple 

 or bear branches. 



Sori oblong or linear, each borne on a mid vein's primary 

 branch when this is simple, when it is compound extending along 

 or wholly upon its superior basal branch or extending along or 

 wholly upon a veinlet of the latter next the mid vein, opening 

 toward the midvein: indusia whitish, delicately membranous, 

 subentire or undulate or irregularly crenate. 



Spores marked with anastomosing ridges or verrucose or 

 papillose with ridges reduced or lacking. 



Habitat. Seams, pockets, and ledges of shaded cliffs, par- 

 ticularly limestone. 



Range. Nova Scotia and eastern coast of Hudson Bay to 

 Alabama, Texas, and Arizona, northwestward to Oregon, British 

 Columbia, and Alaska. 



