8. PTERIDIUM Scopoli, 1760. 
The name Pteridion was applied by Valer. Cordus 
[Hist, de Plantis 2 : 170. 1561] to Phegopteris dryopte- 
rls. The ancient name for the Eagle Pern was with- 
out doubt Thelypteris, 
Rootstock long, creeping, blacki?;h. Leaves usually 
ternate. Sporecases borne in sori upon a revolute jDortion 
of the leaf-margin. Indusium membranous. 
1. P. aquilinum (L )Kuhn. 
Pilix foemina^ foliis^per margines pulverulen- 
tes . . Ban. Cat. ; Ray, Hist. PI. 2 : 1928. 
Pterisfronde supradecomposita . . Gron. Fl. 
Virg. 2 : 197. 
Pteris aquilina L, Sp. PI. 1075. Eaton^ Ferns 
N. Am. I : 263. t. 35; in Gray, Man. 681. 
Underw, in 111. Fl. i : 28. Clute^ Ferns 69. 
Waters^ Ferns 93. 
Pteridium aquilinum Kuhit^ 1879. in Decken's 
Reisen 3 : 11 . Underw, Ferns 9 i ; in Britt. 
Man. 8. 
Eagle Fern. Bracken. 
Plants 5-20 dm. or more high; leaves ovate-triangu- 
lar c5r ternate, 2-3-pinnate at the base ; pinnules various- 
ly lobed, or entire. 
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