628 CLXIV. FILICES. ASPIDIUM. 



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



( of 1 scale, opening outwardly. . Aspidium. 2 



< of 2 scales, l of them marginal. . Dic/csonia. 10 



< superficial, ( of several scales, opening inwardly. Cheilantftes. 8 



( Sori round Undusium < beneath the sorus, fimbriate. , Woodsia. 4 



I or roundish. { Indusium Polypodivm. 1 



( transverse, on the veinlets. . . Asplenium. 3 



Frond pin- ^ not marginal, { parallel with the midvein. . . Woodwardia. 5 



nate, &c. I Sori linear or oblong, closely marginal, continuous Pteris. 7 



( apex long-acuminate, striking root in the ground. .... AspUnrnm. 3 



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



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



TRIBE 1. POL,YPODIACE3 Thecas furnished with a vertical, jointed, 

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

 larly. 



1. POLYPOD1UM. 



Gr. TroAvj, many, Trot)?, foot; from the multitude of its roots. 



Sori roundish, scattered on 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. VTJLGARE. (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.) Triangular 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. 



/?. 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 divisions pinnatifid ; veins much forked. 



4. P. DRYOPTERIS. Ternate Polypod. 



Frond ternate, bipinnate ; branches of the 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. 

 0. calcareum. (P. calcareum. Sm.) Branches of the frond erect, rather rigid. 



2. ASPIDIUM. Swartz. 

 Gr. acriris, 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. 



