FILICES. (FERNS.) 587 



7. E. roUn'aStlim, Braun. Stems 3 -6 high; the ridges narrow, rough 

 with one line of tubercles ; sheaths short, with a black girdle above the base, rarely 

 with a black limb, and about 40 deciduous 3-keded teeth with ovate-awl-shaped points. 

 River-banks, Ohio to Illinois, and southward. Too near the last ; and passes 

 by var. AFFIXE, Engclm. (a smaller plant, with 20-25 awl-pointed more per- 

 sistent teeth) into the next. 



8. E. liyemale, L. (SCOURING RUSH. SHAVE-GRASS.) Stems l- 

 3 high, the ridges roughened by 2 more or less distinct lines of tubercles ; sheat/is 

 donyated, with a black girdle above the base, and a black limb, consisting of 

 about 20 (17-26) narrow/// linear teeth, l-keeled at the base and with awl-shaped 

 deciduous points. Wet banks ; common, especially northward. Used for scour- 

 ing. (Eu.) 



*- Stews low and slender, growing in tufts : sheaths loose or enlarging upwards ; 

 ike summits of their 4-keelcd ovate membranaceous and persistent teeth tipped with 

 a fragile awn or cusp. 



9. E. varicgf&tum, Schleicher. Stems ascending (6' -12' long), simple, 

 from a branched base, 5 - ^-grooved ; the ridges rough with 2 rows of tubercles 

 which are separated by a secondary furrow ; sheaths green variegated with black 

 above ; the 5-9 teetli tipped with a deciduous bristle. Shores or river-banks, 

 New Hampshire (Bellows Falls, Carey) to Wisconsin, and northward; rare. 

 (Eu.) 



10. E. SCirpoidCS, Michx. Stems thread-like (4' -8' high), bent or curved, 

 rough, 3 - 4-groovcd alternately with as many bristle-pointed teeth, and with the 

 same number of intermediate fuirows of equal width ; sheaths variegated with 

 black ; central air-cavity wanting. Wooded hill-sides, New England to Penn- 

 sylvania, Michigan, and northward. (Eu.) 



ORDER 136. FILICES. (FERNS.) 



Leafy plants, with the leaves (fronds) usually raised on a stalk or petiole 

 (called the stipe), rising from a root or mostly from prostrate or subterranean 

 rootstocks. separately rolled up (chrinate) in the bud (except in Suborder 

 III.), and bear in <j, on the veins of their lower surface or along the margins, the 

 simple fructification, which consists of 1-celled spore-cases (sporangia), open- 

 ing in various ways, and discharging the numerous minute spores. (An- 

 theridia and pistillidia formed on the seedling plantlet !) Comprises three 

 very distinct Suborders, which now are by many received as separate 

 families : 



SUBORDER I. POLYPODINE^E. THE TRUE FERNS. 



Sporangia collected in dots, lines, or variously shaped clusters (sori or 

 fruit-dots^) on the back or margins of the frond or its divisions, stalked, 

 cellular-reticulated, the stalk running into a vertical incomplete ring, which 

 "by straightening at maturity ruptures the sporangium transversely on tho 

 inner side, discharging the spores. Fruit-dots often covered (at least when 



