6G4 FiLiCES. (ferns.) 



12. ASPIDIUM, Swartz. Shield-Fkun. Wood-Fern. (PI. 18.) 



Fruit-dots round, borne on the liack or ranly at tlic apex of the veins. Indu- 

 slum loverinj^ the .sporauiu^ia, flat or tiattish, scarious, orbieuhir and peltate at 

 the centre, or round-kidney-shaped and fixed either centrally or by the sinus, 

 oj)eninf; all round the margin. Stipe continuous (not articulated) with the 

 rootstock. — Our species Inivc free veins, and 1-3-pinnate fronds. (Name, 

 danidiof, a small shield, from the shape of the indusium.) 



§ 1. DRY6PTERIS, Adanson. (Nephrodium, Z?!c/i., in part, 7/ooi. Lastrea, 

 Bory.) Indusium round-kidnnj-shapeil, or orbicular with a narrow sinus. 



* Veins simple or simply forked and straiyht : fronds annual, dtcaying in autumn, Vie 



stalks and slender creeping rootstocks nearly naked. ( Thelypteris, Schort. ) 



1. A. Th£l;^pteris, Swartz. Fronds pinnate, lanceolate in outline; pin- 

 luc lioiizoiital or sliy;ht]y recurved, linear-lanceolate, deeply pinnatifid, the lowest 

 paira scarcely smaller ; lobes oblong, entire, obtuse or appearing acute when in 

 fruit from the strongly nvolute margins ; veins mostly forked, bearing the (soon 

 confluent) fruit dots near their middle; indusium minute, smooth and naked. 

 (rolyi)odium 'I'lielypteris, L.) — Marshes: common. Aug. — Stalk 1° long 

 or more, usually longer than the frond, which is of thicker texture than the 

 next, and slightly downy. (Eu.) 



2. A. Noveboracense, Swartz. Fronds pinnate, lanceolate in outline, 

 tapering both ways from the middle ; pinnae lanceolate, the lowest 2 or more jiairs 

 gradually shorter and difexed ; lobes flat, oblong, basal ones often enlarged and 

 incised ; veins simple, or forked in the basal lobes ; fruit-dots distinct, near the 

 margin; indusium minute, the margin glandulifcrous. (Polypodium Nov- 

 eboracense, L. A. thelypterokles, Swaiiz.) — Swamps and moist thickets: 

 common. July. — Frond pale-green, delicate and membranaceous, hairy be- 

 neath along the midribs and veins. 



* * Veins, at least the lowest ones, more than once forked or somewhat pinnatily 



branching; the fruit-bearing veinlets of en obscure or vanishing above the fruit- 

 dot: fronds, at least the sterile ones, ojlen remaining green through the winter: 

 stalks and apex of the thickened rootstock scaly or chaffy, and often the main 

 rhachis also. 

 •*- Fronds small, pinnate: pinna- pinnatifid : indusia very large, persistent. 



3. A. fragrans, Swartz. Fronds (4' -12' high) glandular and aromatic, 

 narrowly lanceolate, with linear-oblong pinnately-partcd pinnrc ; their crowded 

 divisions (2" long) oblong, obtuse, toothed or nearly entire, nearly covered be- 

 neath with th2 very large thin iinbricatcfl indusia, which are orbicular with a 

 narrow sinus, the margin sparingly glandulifcrous and often ragged. — Falls of 

 the St. Croix, Wisconsin, Dr. Parry : Wisconsin River, iMpliam, Berlin Falls, 

 N. Hampshire, //. Willey, Mt. Kineo, Maine, C. E. Smith, and northward. — 

 Rootstock stout, nearly erect, densely chaffy, as are the crowded stipes and rhachis. 

 -t- !»- Large (l°-2i° high), the fronds mostly twice pinnate with variously toothed 



and incised pliinnlis : indusia rather small, shrivelled in age, or deciduous. 



4. A. spinulbsum, Swartz. Stipes with a few /)a/e-/»ow/!(/ec/(/«(;i(.v.sa;/M,- 

 frond ovate-lanceolate, twice pinnate ; pinme oblique to the rhachis, elongated-Irian- 



