442 FILICES. (TRUE FERNS.) 



6. PTERIS, L. BRACKEN. 



In ours the rootstock is cord-like, and the fronds scattered, ternate, with 

 decompound divisions. 



1. P. aquilina, L. Frond often very large, subcoriaceous, broadly tri- 

 angular, primary divisions stalked ; pinnae mostly pinnately lobed with several 

 to many rather short obtuse lobes, and with a sometimes very long subentire 

 apex. Common everywhere, being the most widely distributed of ferns. 



7. ADI ANT UM, L. MAIDENHAIR. 



Stalk mostly blackened or very dark purplish-brown and commonly highly 

 polished. 



1 . A. Capillus-VeneriS, L. Fronds pyramidal, with the rhachis continuous 

 to the terminal pinnule, 9 to 1 8 inches long, often pendent, ovate or ovate-lanceo- 

 late, 2 to 3-pinnate at base ; pinnules wedge-obovate or rhomboid, ^ to 1 inch long, 

 deeply and irregularly incised, smooth; involucres lunulate or transversely 

 oblong. From S. California to Utah, Arizona, Texas, and eastward to Vir- 

 ginia and Florida. In moist rocky places, especially about springs and along 

 water-courses. 



2. A. pedatum, L. Frond often a foot broad ; stalk forked at the top, the 

 branches recurved, and bearing several pinnate divisions on the upper side ; pri- 

 mary divisions 6 to 14, bearing numerous oblong or triangular-oblong pinnules, 

 which have the lower margin entire and the upper more or less lobed ; involucres 

 oblong-lunate or transversely linear. Across the continent and far north- 

 ward, but apparently unreported as yet from our immediate range. In rich 

 moist woods, especially among rocks. 



8. ASPLENIUM, L. SPLEENWORT. 



Fronds varying from simple to highly decompound. 



* Indusium straight or nearly so, attached to the upper side of the vein, rarely 



double. 



i- Fronds once pinnate, the pinnae, numerous and sometimes toothed but not again 

 divided, somewhat rigid: rhachis dark and often polished. 



1. A. TrichomaneS, L. Fronds usually 4 to 6 inches long, narrowly linear, 

 pinnate ; pinnas subsessile, roundish-oval or oval-oblong from an obtusely cuneate 

 or truncate base, entire or crenulate, rarely incised, falling separately from the 

 persistent rhachis. Common throughout the United States and northward 

 into British America. Crevices of shaded rocks. 



2. A. ebeneum, Ait. Fronds 9 to 18 inches high, linear-oblanceolate, pin- 

 nate ; pinnae 6 to 18 lines long, firmly membranaceous, mostly alternate, sessile, 

 spreading, oblong or oblong-linear, somewhat auricled, crenately serrate or incised: 

 sori near the midvein. Greenhorn Mountains, Colorado ( Greene), Indian Ter- 

 ritory, and eastward to Canada and Florida. 



