682 FILICES. (FERNS.) 



what membranaceous indusium. Mountains of Va. and Ky. ; thence west and 

 southward. Stipe and rhachis rather stout, brown, covered with narrow chaffy 

 scales and whitish hairs. 



4. C. Ianugin6sa, Nutt. Stipes slender, at first hairy, black or brown, 

 shining ; fronds (3 -6' high) ovate-lanceolate, woolly with soft whitish distinctly 

 articulated flattened hairs, becoming smoother above, twice or thrice pinnate; 

 pinnae (5-6" long) ovate, the lowest distant, the others contiguous; pinnules 

 crenately pinnatifid, or mostly divided into minute and roundish densely 

 crowded segments (-J--1" long), the herbaceous margin recurved forming an al- 

 most continuous indusium. In dense tufts, on dry rocks and cliffs, HI. to Minn., 

 thence west and southward. 



6. PELL .33 A, Link. CLIFF-BRAKE. (PL 16.) 



Sporangia in roundish or elongated clusters on the upper part of the free 

 veins, distinct, or confluent laterally so as to imitate the marginal continuous 

 line of fructification of Pteris, commonly covered by a broad membranaceous 

 and continuous (rarely interrupted) general indusium, which consists of the 

 reflexed and altered margin of the fertile pinnule or division. Small ferns, 

 with 1 - 3-piunate fronds, the fertile ones with narrower divisions than the 

 sterile, but otherwise similar. Stipes generally dark-colored, smooth and 

 shining. (Name from ireAAos, dusky, alluding to the stipe.) 



1. P. gracilis, Hook. (PI. 16.) Fronds smooth (3 - 6' high), delicately 

 membranaceous and slender, of few pinnae, the lower ones once or twice pin- 

 nately parted into 3-5 decurrent divisions, those of the fertile frond oblong 

 or linear-oblong, entire or sparingly incised ; of the sterile ovate or obovate, 

 crenate or incised; veins of the fertile fronds mostly only once forked. 

 Shaded calcareous rocks, Mass, to Minn., and northward; rare. July. 

 Rootstock very slender, creeping; stipes polished, brownish, darker and 

 sparingly chaffy at base. 



2. P. atropurptirea, Link. Smooth, except some bristly-chaffy hairs 

 on the midribs and especially on the dark purple and polished stalk and rhachis, 

 6-15' high ; frond coriaceous, pale, once or below twice pinnate ; the divisions 

 broadly linear or oblong, or the sterile sometimes oval, chiefly entire, some- 

 what heart-shaped or else truncate at the stalked base; veins about twice 

 forked. Dry calcareous rocks; not common, but of wide range. July. 

 Rootstock short and stout ; stipes clustered. 



7. CRYPTOGRAMME, R. Brown. ROCK-BRAKE. 



Fruit-dots roundish or elongated and extending far down on the free forking 

 veins. True involucre or indusium none, the herbaceous margins of the fertile 

 segments at first reflexed and meeting at the midrib, at length opening out flat 

 and exposing the confluent sporangia. Low ferns, with smooth, 2 - 3-pinnate 

 fronds, the fertile ones taller than the sterile, and with much narrower divis- 

 ions. (Name from Kpvirros, hidden, and ypafj.^, a line, alluding to the lines 

 of sporangia at first concealed by the reflexed margin.) 



1. C. acrostichoides,R. Brown. Stipes densely tufted, straw-colored ; 

 fronds 2 -3-pinnate (6-1 (/high); fertile segments stalked, linear or linear- 

 oblong (3-5" long), the sporangia in lines extending down the veins almost 



