EQUISETACEAE 391 



ik stems usually taller and more slender, the joints nearly all furnished with 

 verticils of branches which are longer, and considerably subdivided. 

 Hub. Low grounds ; borders of woods : frequent. Fr. Mny. 



g 2. Stems evergreen, all alike, and mostly branchless. 



3. E. hyemsile, L. Steins rather stout, very rough; sheaths 

 short, close, whitish, with small blackish deciduous teeth at sum- 

 mit. 

 WINTER EQUISETUM. Scouring Rush. 



Stems 1 to 2 feet high, glaucous (purplish-black at base), terminating in an 

 ovoid blackish spike about half -an inch in length ; shettths whitish, with a purplish 

 black band at base, and at summit a ring of small blackish teeth, which soon 

 fall off, leaving the sheath truncate and entire. 

 Hub. Margins of Swamps : frequent. Fr. June. 



ORDER CXX. FILTCES. FERNS. 



Plants consisting chiefly of horizontal rhizomas, and stipitute leaf-lile expansions, 

 called fronds, which are mostly circinate in the bud, and bearing on the veins of 

 their lower surface, or along, the margips, the simple Jructijication, which consists 

 of 1-celled sporanges, opening in various ways, and discharging the numerous 

 minute spores. 



SUBORDER I. POLYPODIN'EAE. 



Sporanges collected in dots, lines, or variously shaped clusters (called sori), on 

 the back or margins of the frond,or its divisions, reticulated and pellucid, pedi- 

 cellate, surrounded by an. elastic vertical ring, and which by straightening at 

 maturity ruptures the sporange tranversely on the inner side, discharging the 

 spores ; sort often covered by a membrauaceous scale, or modified margin of the 

 frond, which is termed the indu&ium. 



1. POLY PODIEAE : Sori without a special indusium, orbicular. 



511, POL.YPOWUIH, L. 



[Gr. Poly, many, and Pous, a foot ; from its numerous stipes.] 



Sort scattered irregularly on the back of the frond ; veins simple, 



forked, or pinnate. Rhizoma covered with tawny chaff-like scales. 



f Fronds simply pinnatifid, evergreen ; sori large. 



1. P. Ylllg&re, L. Fronds lance-oblong, smooth, deeply pin- 

 natifid ; pinnae linear-oblong, obtuse, crenate-serrulate. 

 COMMON POLYPODIUM. 



Fronds 4 to 8 or 10 inches long, and 1 to 2 inches vdde; stipe (or petiole) naked 

 and smooth, flattish and somewhat channelled on the upper side. Sori in 2 rows 

 on the back of each segment, distinct, or finally in contact. 

 Hub. Rocky woodlands : frequent. Fr. July. 



f f Fronds bipinnatiful, annual ; sori small. 



2. P. hexagonopterum, MX. Fronds broadly triangular; 

 lower divisions connected by an oblong hexagonal wing. 

 HEXAGONAL-WINGED POLYPODIUM. 



Fronds 6 to 9 inches long, and about the same width, at base, forming, in their 

 outline, a nearly equilateral triangle; pinnae lanceolate, pinnatifid; stipe 8 to 12 

 or 15 inches long, slender, naked. Sori distinct, somewhat in 2 rows, but often, 

 irregular, on the back of the \&nce-ob\on% pinnules. 

 Ifab. Moist woodl ands, and thickets : frequent. IV. July. 



