134 FLORA OF THE UPPER SUSQUEHANNA. 



E. sylvaticum L. Wool) Horsetail. Abundant in moist wood- 

 lands. Sterile stems producing several very regular whorls of 

 branches. The most beautiful member of the genus in our 

 region. 



E. fluviatlle L. Pipes. Swamp Horsetail. Plentiful on the 

 borders of lakes, streams and ditches, often in shallow water. 

 Stems frequently unbranched, but usually producing a few 

 straggling branches near the summit of the stem. {E. Ivnosum 

 L.) 



E. hyemale L. Scouring Rush. Shave Grass. Plentiful in low 

 woodlands, on the banks of streams, and other moist places. 

 Stems commonly unbranched, stiff, two feet or more high, per- 

 sisting through the winter. 



E. variegatum Schleich. Rare. Brisbin swamp on the margin of 

 a sand slide, Coville. The only station. 



FILICES. 



POLYPODIUM L. 



V, vulgare L. Common Polypody. Plentiful in our region 

 wherever outcrops of rock occur. Usually found growing on the 

 tops of rocks where there is little moisture. Fronds nearly pin- 

 nate, evergreen, leathery ; the large, round fruit dots on the 

 under side of the fronds in late summer. 



ADIANTUM L. 



A. pedatum L. Maikenhair Fern. Abundant throughout in 

 moist, rich woodlands. Stipe a foot or more high, black and 

 shining, divided at the top into two curving branches which bear 

 the pinnte. Fruit beneath a reflexed portion of the pinnule. 

 Much prized for cultivation. 



PTERIS L. 



P. aquilina L. Bra* ken. Brake. Eagle Fern. Most abun- 

 dant on scrubby hillsides, on the borders of fields, roads and 

 in open woods. Stipe stout and tall, at top bearing three di- 

 visions, variously subdivided. Rootstock stout, creeping ex- 

 tensively, bearing the fronds at intervals, all summer. Fruit 

 produced in a line on the margin of the pinnules. 



