FiriCES. (FEENS.) 597 



crowded. Indusium flat, scarions, orbicular or round-kidney-shaped, coyering 

 the sporangia, atfiched to the receptacle at the centre or at the sinus, opening 

 all round the margin. — Fronds mostly 1 -3-pinnate. (Name aoTriSiov, a small 

 shield, from the shape of the indusium.) 



§ 1. DliYOPTEEIS, Adans., Schott. (Nephradium, Skh. in part. Lastrea, 

 Bori/. ) — Indusium round-kidney-shaped, or orbicular with a narrow sinus, fixed at 

 the sinus : fronds membranaceous or thinnish. 



* Veins simple or simply forked and straight : fronds annual, decaying in autumn, 



the stalks and creeping rootstocks nearly naked. (Thelyptcris, Schott.) 



1. A. XlielypteriS, Swartz. Frond pinnate, lanceolate in outline; the 

 slightly reflexed or horizontal pinnoe gradually diminishing in length from near the 

 base to the apex, sessile, linear-lanceolate, deeply pinnatifid, with oblong nearly 

 entire obtuse lobes, or appearing acute from the strongly revolute margins in fruit; 

 vdns mostly forked, bearing the crowded fruit-dots (soon confluent) near their mid- 

 dle. (Polypodium Thelypteris, L.) — Marshes; common. Aug. — Stalk 1° 

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

 the next, slightly downy ; the fruitrdots soon confluent and covering the whole 

 contracted lower surface of the pinnse. (Eu.) 



2. A. Noveboracense, Willd. Frond pinnate, oblong-lanceolate in out- 

 line, tapering below, from the lower pinnae (2 - several pairs) being gradually shorter 

 and dejiexed ; the lobes flat, broadly oblong ; their veins all simple except in the 

 lowest pairs, bearing scattered _/raif-(fote (neoer confluent) near the margin. (Poly- 

 podium Noveboraoense, L. A. thelypteroides, iSaJorte.) — Swamps and moist 

 thickets ; common. July. — Frond pale green, delicate and membranaceous, 

 nearly as the last, except in the points mentioned. 



* * Veins, at least tlie lowermost, more than once forked or somewhat pinnately branch- 

 ing ; the fruit-bearing veinhts often obscure or vanishing above the fruit-dot : fronds, 

 at least the sterile ones, often remaining green through the winter : stalks and apex 

 of the scaly thickened rootstocks chaffy, and often the main rhachis also when young. 



4- Frond twice pinnate and with the pinnules pinnatifid or deeply iiKised : indu- 

 sium deciduous. 



3. A, spinillosmn, Swartz. Frond oblong or ovate-oblong in outline 

 (l°-2° long), lively green, smooth; pinnules oblong or oblong-linear, mostly 

 obtuse, horizontal, crowded, the lower deeply pinnatifid into linear-oblong obtuse 

 lobes which are sharply cut^toothed, the upper cut-pinnatifid or incised, with the 

 shorter lobes few-toothod at the apex ; margin of the indusium denticulate or 

 beset with minute stalked glands. (A. intei-medium, Muhl. Dryopteris inter- 

 media ed. I.) — Woods, everywhere common. July. — Exhibits a variety of 

 forms some of them clearly the same as the European plant, more commonly 

 intermediate in appearance between it and 



Var. dilatatuni. Frond broader, ovate or triangular-ovate in outline ; 

 pinnules lance-oblong, the lower sometimes pinnately divided ; indusium smooth 

 and naked. (A. dilatatum, Willd.) — A dwarf state, fruiting when only 5' -8 

 hio'li answers to var. (of Lastrsea dilatata) dumetorum. A peculiar form (A. 

 campylopterum, Kunze? and Dryopteris dilatata, chiefly, ed. 1) has the pinnai, 

 pinnules, and their divisions remarkably crowded, and directed obliquely forwards 



