14 FLOBA OF PHILADELPHIA. 



2. Filix fragilis (L.) Underw. M. p. 17. Shaded cliffs and rocky woods. 

 Summer. 

 General, but not in southern New Jersey except Burlington — Medford 

 (Br.). 



13. WOOD^IA E. Br. . 



Indusium minute or evanescent, flat, concealed beneath the sorus, its. margin 

 cleft into slender hair-like segments. ,.,,..,,, 1. W. Ilvensis. 



Indusium distinct, at first enclosing the spor'ariges, splitting into jagged 

 lobes. 2. W. obtusa. 



1. Woodsia Ilvensis (L.) B. Br. M. p. 18. Exposed rocks. Summer. 



Bucks— Nockamixon. Chester— Black Eoek' (PLC). Lehigh— Kern's 

 Mill, near Whitehall (Kr.). 



2. Woodsia obttjsa (Spreng.) Torr. M. p. 18. Bocks. Summer. 



14. DENNSTAEDTTA Bernh. 



1. Dennstaedtia punctilobula (Michx.) Moore.. M. p. 19. Open places. 

 Summer. 



15„ MATTEUCPIA , Todaro. 



1. Matteuccia Struthiopteris (L.) Todaro. Ostrich Fern. M. p. 19. 

 Alluvial soil.. Summer. 

 Philadelphia— Upper Wissahtibkori (Be.). Bucks— Nockamixon. Lan- 

 caster—York Furnace (Br.);' Lehigh— Coplay (Kr.). 'Northampton — 

 (P.) . Dauphin— '(P.) . "' ', , 



, Burlington— Grosswick's Creek (C). Hunterdon— Eosemont, Bull's 

 Island, Frenchtown, Lambertville (C). ; 



■.., - 16. ONOCLEA L. •; •,.•■ 



1. Onoclea sensibilis L. Sensitive Fern. M. p. 19. Moist soil. Summer. 



Order 2. SALVINIALES. 

 Family 1. MARSILIACEAE R. Br. 



1. MAESTLIA L. 



1. Marsilia quadrieoha -L. M. p. 20, JCn, water. Summer.. 

 Delaware— Cram. Lynn (Le,.)., ,• 



Order 3. EQUISETALES. 

 Family 1. EQUISETACEAE Michx., Horsetail Family. 



1. EQUISETIJM L. Horsetail. 



Stems annual; stomata scattered;, 



Stems of two kinds, the fertile appearing , in early spring before the 

 sterile. 

 Fertile stems simple, soon withering; sheaths of branches of sterile 



stems 4-toothed.i 1. E. arvense. 



Fertile stems branched when old, only the apex withering. 



2. E. syVoaticum. 



