POLYPODIAOEAE (FERN FAMILY) 39 



the slender stipe brownish and passing into a green herbaceous rhachis. — Shaded 

 limestone ; Nfd. to n. N. E., w. and iiorthw ; rare. (Widely distr.) 



3. A. Trich6manes L. Fronds (8-22 cm. long) in dense spreading tufts, 

 linear in outline, dark green and more rigid ; pinnae roundish-oblong or oval 

 (3-7 mm. long), entire or crenulate, rarely incised, unequal-sided, obliquely 

 wedge-truncate at base, attached by a narrow point, the midvein forking 

 and " evanescent ; the thread-like stipe and rhachis purple-broicn and shin- 

 lYig^ — Shaded rocks. July. (Widely distr.) Forma incisum Moore with 

 deeply pinnatifid pinnae has been reported from Vt. {Miss Grout., Mrs. Horton). 



-t- -t- Pinnae more or less auricled. 



4. A. parvulum Mart. & Gal. Fronds upright (1-25 dm. high), narrowly 

 linear-oblanceolate ; pinnae (4-12 mm. long) rigid and thickish, mostly opposite, 

 nearly sessile, somewhat detlexed^ oblong, obtuse, entire or crenulate, auricled 

 on the upper or both sides ; sori rather few, as near the margin as to the continu- 

 ous midvein ; stipe and rhachis black and shining. {A. resiliens Kunze.) — Mts. 

 of Va. to Kan., and southw. — Intermediate between the last and the next. 



5. A. platyneuron (L ) Oakes. Fronds upright (2-5 dm. tall), linear- 

 oblanceolate in outline, fertile ones much the taller ; pmnae (1-3 cm. long) 

 firmly membranaceous, mostlii alternate, sessile, spreading, oblong or oblong- 

 linear, finely serrate or even incised, the base auricled on the upper or both sides ; 

 sort many, nearer the elongated midvein than the margin ; stipe and rhachis 

 blackish-purple and shining. (A. ebentum Ait.) — Rocky open woods, s. Me. 

 to Col., and southw. (W. I., S. Am., Afr.) Var. serrXtum (E. S. Miller) 

 BSP. is a form with at least some of the pinnae deeply jagged-serrate. Var. 

 iNcisTM (E. C. Howe ) Robinson has very brittle stipes and the pinnae deeply 

 pinnatifid. (A ebeneum, var. Mortonae Davenp.) — Vt. to Md., Mo., and 

 "Ark."' ; rare. 



6. A. Bradleyi D.C.Eaton. Fronds oblong-lanceolate (4-20 cm. tall); stipe 

 blackish and somewhat shining ; pinnae membranaceous, rather numerous, the 

 lower ones no larger than the middle ones, all short-stalked, oblong-ovate, obtuse, 

 incised or pinnatifid into oblong toothed lobes. — On rocks, e. N. Y. to Ky., 

 " Mo.," and southw. ; rare. 



* * * Fronds ovate-lanceolate to deltoid, 2-S-pin7iate or -pinnatifid. 



7. A montanum Willd. Fronds ovate-lanceolate from a broad base (5-13 

 cm. long), subcoriaceous, pinnate ; pinnae ovate-oblong, the lowest pinnately 

 cleft into oblong or orate cut-toothed lobes, the upper gradually simpler ; rhachis 

 green, broad and flat ; stipe brown at base. — Cliffs and rocks, from Ct. to 

 O., Ky., "Ark." and southw. Jidy. 



8. A. Ruta-muraria L. Fronds deltoid-ovate (S-1 cm. long exclusive of the 

 green stipe), subcoriaceous, laxly 2-3-pinnate at base, the pinnae alternate; 

 ultimate segments few, stalked (3-14 mm. long), from narrowly cuneate to 

 roundish-obovate, toothed or incised at the apex ; veins forking ; sori 2-4 on a 

 segment; rhachis and stipe green. — Limestone cliffs, Vt. to Ont., Mich., Mo., 

 and southw. ; scarce. July. (Eurasia.) 



§ 2. ATHYRIUM (Roth) J. Sm. Indusium straight or more often curved^ fre- 

 quently crossing the vein ; fronds tall, strictly herbaceous ; the stipes green 

 or greenish not filiform, the Inmdles concentric and uniting above into a 

 S-A-arjned central bundle; scales delicate, of thin-walled cells. — Athyriuni 

 Roth as redefined by Milde. 



* Fronds simply pinnate ; indusium straight or but slightly curved. 



9. A. angustifblium Michx. Fronds 6-12 dm. high ; pinnae (8-12 cm. 

 long) numerous, short-stalked, linear-lanceolate, acuminate, entire or crenulate, 

 those of the fertile frond narrower; fruit dots linear, 20-40 each side of the 

 midvein ; indusia slightly convex. (Athyrium Milde.) — Rich woods, w. Que. 

 and N. H. to Minn., and southw. Sept. 



* * Fronds bipinnatifid ; indusium straight or slightly curved. 



10. A. acrostichoides Sw. Fronds (6-11 dm. high) pinnate; pinnae deeply 



