92 Our Native Ferns. 



ing contiguous sori near the middle, soon covering the entire sur- 

 face. A form with cut-lobed, often strongly falcate pinnae, set 

 obliquely to the rachis, and with the tips of nearly all bearing 

 sori, is the var. incisum, Gray. N. Eng. to Fla., Miss, and north- 

 ward. III. 



i8. A. munitum,* Kf. Stipes 4' — 12' long, chaffy like the 

 rachis with brown scales ; fronds growing in a crown, 1° — 4° long, 

 tapering slightly toward the base ; pinnse numerous, linear-acu- 

 minate, 3' — 4' long, very sharply and often doubly serrate, with 

 appressed needle-like points ; sori numerous forming a single row 

 each side of the midrib half-way to the margin. Cal. and north- 

 ward. IV. 



Var. NUDATUM, D. C. Eaton. Fronds smaller, the scales al- 

 most entirely lacking; pinnae few, rather remote, short and broad, 

 the teeth closely appressed; sori scanty on the ends of the upper- 

 most pinnae. Cal. IV. 



Var. IMBRICANS, D. C. Eaton. Fronds small not narrowed at 

 the base ; pinnae crowded, lanceolate-oblong, pale, ascending and 

 imbricated ; sori nearer the margin than the midvein ; stipes with 

 brown scales at the base, otherwise almost naked. Cal. IV. 

 W Fronds scarcely stalked, linear-lanceolate. 



ig. A. Lonchitis, Swz. Fronds 9' — 20', rigid ; pinns i' or 

 more long, broadly lanceolate-falcate or the lowest triangular, 

 strongly auricled on the upper side, the lower obliquely truncate, 

 densely spinulose-toothed ; sori contiguous and near the margin. 

 Canada and Wis. to Utah, and northward. II. 



**Fronds bipinnate or nearly so. 



20. A. mohrioides, Bory. Stipes tufted, 2'— 6' long, more or 

 less densely clothed with lanceolate dark-brown scales ; fronds 

 6' — 12' long, 2' — 3' broad, with numerous dense, often imbricated, 

 lanceolate pinnae, which are cut below into slightly toothed ob- 

 long-rhomboidal pinnules; teeth blunt or mucronate; texture 

 coriaceous ; both surfaces naked ; rachis stout, compressed, scaly ; 

 veins close, immersed ; sori copious. Cal. IV. 



21. A. aculeatum, Swz. Rhizoma stout, erect; stipes vari- 

 able in length, very chaffy with large and small scales intermixed 

 as in the rachis ; fronds 1° — 2° long, growing in a crown, oblong- 

 lanceolate, pinnate ; pinnae closely placed, lanceolate from a broad 

 base, mostly curved upwards, incisely pinnatifid or again pinnate ; 

 segments or pinnules of variable shape, oval-rhomboidal, or un- 

 equally triangular-ovate and auriculate on the upper side of the 

 slightly stalked base, the teeth aculeate in various degrees ; under 



