128 OUR NATIVE FERNS AND THEIR ALLIES. 



5. E. palustre L. Stems slender, 10' 18' high, very deep- 

 ly 5 9 grooved, the grooves separated by narrow, wing-like 

 ridges, roughish ; sheaths with about 8 lance-awl-shaped, whit- 

 ish margined teeth; branches few in a whorl, with mostly 5- 

 toothed sheaths. (E. pratense Reichenb.) Western New York 

 and Wisconsin to British Columbia and northward. 



6. E. li to rale Kuhl. Stems slightly roughened, 6 19 

 grooved, the carinae convex ; sheaths sensibly dilated above, the 

 uppermost bell-shaped ; leaves convex, angled beneath, sepa- 

 rate at the commisural groove ; teeth herbaceous, membranous 

 at the margin, narrow, lanceolate ; branches of two kinds, the 

 4-angled hollow, the 3-angled solid, first joint a little longer or 

 shorter than the sheath of the stem ; spores abortive, elaters 

 usually wanting. Bay of Quinte, Canada (Macoun); Vermont 

 (Pr ingle); Oswego River, New York (Wibbe). 



ft Sheaths appressed. 



7. E. fluviatile L. Stems 2 3 high, slightly many-fur- 

 rowed, smooth, usually producing upright branches after fruc- 

 tification ; sheaths appressed, with about 18 dark-brown, short, 

 acute, rigid teeth ; air-cavities wanting under the grooves, small 

 under the ridges. Includes E. limosum L. (E. uliginosum 

 Muhl., E. heleocharts Ehrh.) Virginia to Washington Terri- 

 tory and northward. 



2. HlPPOCH^ETE. Stems perennial, evergreen; spikes tipped 

 with a rigid point ; stomata in regular rows ; fruiting in 

 summer. 



* Stems tall and stout, tisually many-grooved. 

 t Branches numerous, regularly "whorled. 



8. E. ramosissimum Desf. Stem grooved, more or less 

 roughened, 6 26 furrowed ; ridges marked with bands; sheaths 

 dilated, teeth not grooved, leaving a triangular, rarely truncate 

 margin ; leaves 3 4 carinate ; branches usually copious and 

 whorled, 49 angled ; series of stomata in 14 lines. British 

 Columbia (Lyall). 



9. E. Mexicanum Milde. Stems rough, slender, inclined 

 or somewhat erect ; 20 24 furrowed, the ridges very narrow; 

 sheaths long, cylindric, truncate; teeth grooved; leaves flat; 

 branches more or less irregularly whorled, 6 9 angled ; stomata 



