44 Polypodiaceae Cystopteris 



2. Cystopteris fragilis (L.) Bernh. {Filix fragilis (L.) Underw.) 

 Brittle Fern. Map 11. This species prefers the deep, rich leaf mold of 

 beech and sugar maple and white oak woods and is frequent to common 

 throughout the state south of the Wabash River where woods of this kind 

 are found. North of the Wabash River it is infrequent to very rare. It is 

 absent in the southern part of the state in the areas where low, flat woods 

 occur. It is found in exposed places on sandstone ridges and bluffs. 



Students sometimes find difficulty in distinguishing this species from 

 Woodsia obtusa. The stipe of the last named species is covered more or 

 less densely with short, stipitate glands while the stipe of Cystopteris is 

 entirely glabrous or with only a few glands near the summit. 



The Cystopteris fragilis species complex has been restudied by C. A. 

 Weatherby. He has recently described a new variety to which, in my 

 opinion, all or most all of our specimens belong. It is described as follows : 



"Cystopteris fragilis (L.) Bernh. var. protrusa Weatherby. (Rhodora 

 37: 373-375. 1935.) Rootstock creeping, only sparsely beset with bases 

 of old fronds, the growing point hardly paleaceous, produced 2-4 cm beyond 

 the fronds of the season ; well-developed blades nearly bipinnate-pinnatifid, 

 11-22 cm long, 5-11.5 cm wide, pinnae ovate to ovate-lanceolate, acute, 

 pinnules toward the base of the pinnae deltoid-ovate to ovate-lanceolate, 

 subacute, usually shortly but distinctly petiolulate, deeply pinnatifid into 

 oblong, obtuse lobes ; in juvenile or depauperate blades less lobed and more 

 obtuse; indusium about 0.5 mm long, shallowly lobed or nearly entire at 

 apex. Southern New York, south in the piedmont and the mountains to 

 Alabama, west to Minnesota and Missouri." 



My specimens have been examined by two fern specialists and they 

 agree that most of them belong to this variety and some can not be deter- 

 mined with certainty. 



A form of this species with large, abundant sori has been named f. 

 magnasora Clute (Fern Bull. 9: 65. 1901). 



The true species has a range to the north of Indiana. In order to refer 

 specimens to their correct variety and form it is usually necessary for 

 them to have the indusium and rootstock which most of our specimens lack. 

 Since it is impossible to correctly name all of our specimens I have decided 

 that it is best to regard all of them as belonging to a species complex and 

 they are so indicated on the map. 



Newf. and Lab. to Alaska, southw. to Ga., Ala., Kans., Ariz., and s. Calif. 



3. PTERfiTIS Raf. 



Rachis glabrous throughout its entire length or only glabrate above the lowest pinnae 

 and polished below them 1. P. nodulosa. 



Rachis more or less puberulent to pubescent throughout, at least above the lowest 

 pinnae; rachis below the lowest pinnae usually not polished 



la. P. nodulosa f . pubescens. 



1. Pteretis nodulosa (Michx.) Nieuwl. (Rhodora 21: 178. 1919.) 

 (Onoclea Struthiopteris and Matteuccia Struthiopteris of most authors.) 

 Ostrich Fern. Map 12. This species is, no doubt, very local in the 



