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. AD I 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 18 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 afoot 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. 



H Fronds once pinnate, the pinna; 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 ; pinnae subsessile, roundish-oval or oval-oblong from an obtusely cuneate 

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

 persistent rhachis. -7- 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. 



