628 CLXIV. FILICES. Aspidium. 



* ♦ Fronds sometimes contracted, but never paniculate or spicate, 



(of 1 scale, opening outwardly. . Aspidium. 3 



< of 2 scales, i of them mar^ind. . Dicksonia. 10 



\ superficial, ( of several scales, opening inwardly. Cheilanthes. 8 



fSori round Hndusium ( beneath the sorus, fimbriate. .... Woodsia. 4 



j or roundish. { Indusium Pohjpodiwm. l 



\ Uransverse.on the veinlets. . . Aspienium. 3 



Prond pin- 1 $ not marginal, I parallel with the midvein. . . Woodwardia. 5 



nate. &c. ISorilinear or oblong, (closely marginal, continuous Pteris. 7 



J apex long-acuminate, striking root in the ground. .... Asplenium. 3 



Frond entire, ( apex acute, not rooting. Sori linear, scattered Scolopendrium. 6 



Frond pedate, on a black, polished, bifurcate stipe. Adiantum. 9 



Tribe 1. POIiYPODIACEiE. — Thecae furnished with a vertical, jointed, 

 elastic, and usually incomplete ring, and bursting transversely and irregu- 

 larly. 



1. POLYPODIUM. 



Ch". TToXvff, many, ■novs^ foot; from the multitude of its roots. 



Sori roundish, scattered oji various parts of the under surface of 

 the frond ; indusium none. 



1. P, iNCANUM. Pursh. (P. ceteraccinum. Mx. Acrostichum polypodoi- 

 des, Linn.') — Fronds deeply pinnatifid; segments alternate, linear, very 



entire, obtuse, scaly beneath, the upper ones gradually smaller; stipe scaly, 

 bearing the fertile segments near the apex ; sori solitary and distinct. — A para- 

 sitic fern, 3 — 6' high, growing on the inclined, moss-clad trunks of living trees, 

 particularly of the huge sycamores, to the height of 10 — 20 feet. In the damp 

 forests along rivers, Western States ! and also Southern. 



2. P. vuLGARE. (P. Virginianum. Willd.) Common Polypod. 



Frond deeply pinnatifid, smooth ; segments linear-oblong, obtuse, crenu- 

 late, the upper ones gradually smaller ; sori large, distinct. — Rather common 

 on shady rocks and in woods, forming tangled patches with their roots which 

 are clothed with membranous scales. Fronds nearly a foot high, divided into 

 alternate segments nearly to the midvein. Stipe naked and smooth. Segments 

 parallel, a little curved, about \' wide. Fruit in large, golden dots in a double 

 row, at length brownish. July. 



3. P. Phegopteris, (P. connectile. Mx.) T^riangular Polypod. 

 Frond bipinnatifid, slightly pubescent and ciliate, of a triangular outline, 



the 2 lower leaflets or pinnae deflexed ; subdivisions lanceolate, obtuse, the 

 upper ones entire, lower incisely crenate, lowest adnate-decurrent ; sori minute, 

 distinct, solitary. — A fern in low woodlands, remarkable for the broad triangu- 

 lar outline of its fronds. These are about a foot in height, and rendered a little 

 hastate by the lower leaflets (which are broadest) being deflexed. Divisions 

 acuminate, connected at base by the lower segments. Stipes smooth. Aug. 



/S, connectile. (P. connectile. Mx.) Somewhat rigid; segments of the lower 

 divisions all subentire ; veins nearly simple. 



y. hexagonopterum. (P. hexagonopterum. Mx.) Texture more delicate ; 

 segments of the lower divisio7is pinnatifid ; veins much forked. 



4. P. Dryopteris. Tcrnate Polypod. 



Frond ternate, bipinnate ; branches of Ike frond spreading, deflexed, seg- 

 ments obtuse, subcrenate ; sori marginal ; root filiform, creeping. — This beauti- 

 ful fern grows in shady places and mountainous woods. Rare. Root black 

 and very slender. Stipe slender and delicate, smooth, nearly a foot high, divid- 

 ing into 3 light green, drooping, compound leaflets of a very delicate texture. Jl. 

 p. calcarcuni. (P. calcareum. Sni.) Bra7ichcs of the frond erect, TSLther rigid. 



2. ASPIDIUM. Swartz. 



Gr. acrris, a small shield ; from the form and position of the indusia. 



Sori roundish or elliptical, scattered ; indusium orbicular and um- 

 bilicate (fastened at the centre and opening all around), or reniform, 

 fastened on one side and opening on the other. 



