FiLicES. (ferns.) 655 



§ 2. Evergreen or perennial-stemmed, surviving the ivinter, mostly rough (the cuticle 

 abounding in silex) : fruiting in summer : spike tipped with a rigid Utile point. 

 (Stomata in regular rows, in our species \-rowed an each side of the groove. 



» Stems tall and stout (1^° - 4° or even 6° high), simple or casually branched, evenly 

 many- {15-40-) grooved: sheaths appressed. (Probably all forms of the Com- 

 mon Scouring Rush.) 



7. E. ISBvigktum, Braun. Stems lJ°-4° high, sometimes with numer- 

 ous branches ; the ridges convex, obtuse, smooth or minutely roughish with minute 

 tubercles ; sheaths elongated, with a narrow black limb and about 22 liumr-awl- 

 shaped caducous teeth, l-keeled below. — Dryish clay soil, Illinois and southward. 



8. E. robtistum, 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-keeled teeth with ovate-awl-shaped 

 points. — River-banks, Ohio to Illinois, and southward. — Passes by var. affIne, 

 Engelm. (smaller, with 20-25 awl-pointed more persistent teeth) into the next. 



9. E. hyemkle, L. (Scouring-Rush. Shave-Grass.) Stems 1J°-4° 

 high ; the ridyes roughened by 2 more or less distinct lines of tubercles \ sheaths 

 elongated, with a black girdle above the base and a black limb, of about 20 (17 - 

 26 ) narrowly linear teeth, 1 -keeled at the base and with awl-shaped deciduous points. — 

 Wet banks : common northward. Used for scouring. (Eu.) 



» * Stems slender, in tufts, 5 - \0-grooved: sheaths looser. 



10. E. variegitum, Schleicher. Stems ascending (6' - IS' long), usually 

 simple from a branched base, 5 - 10-grooved ; sheaths green variegated with 

 black above ; the 5 - 10-teeth tipped with a deciduous bristle. — Shores or river- 

 banks. New Hampshire (Bellows Falls, Carey) and Niagara to Wisconsin and 

 northward : rare. (Eu.) 



11. E. BCirpoldes, Michx. Stems very numerous in a tufl, filiform (3' -6' 

 high), flexuous and curving, mostly 6-grooved, with acute ridges; the sheaths 

 3-tooihed, the bristle-pointed teeth more persistent ; central air-cavity wanting. — 

 Wooded hillsides, New England to Pennsylvania, Michigan, and northward. 

 (Eu.) 



Order 130. FIliICES. (Fbrns.) 



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

 (stipe), rising from a root, or mostly from a prostrate or assurgent or even 

 erect rootstock, separately rolled up (circinate) in the bud (except in Sub- 

 order IV.) anSbearing on the under surface, commonly on the veins or along 

 the margins, the simple fructification, which consists of l-celled spore-cases 

 (sporangia), opening in various ways, and discharging the numerous mi- 

 nute spores. (Antheridia and pistillidia formed and fertilization effected 

 on the seeding plantlet !) — Of the eight well-marked Suborders, into 

 which the Ferns are divided, four are represented in the Northern United 

 States. 



The whole order has been elaborated for this edition by Prof. Daniel 

 C. Eaton, of Yale College. 



