PTERIDOPHYTA. 7 



I. POLYPODIUM L. 



Pinnate or simple ferns with stipes articulated to the creeping rootstocks. Sori 

 hemispheric, dorsal, in one or more rows on either side of the midribs. Indusium 

 none. Sporanges pedicelled, provided with a vertical ring which bursts trans- 

 versely. Veins free in the northern species. [Greek, in allusion to the branched 

 rootstocks of some species.] About 350 species, of wide distribution, mostly 

 tropical. 



Lower surface of the leaf glabrous ; plant green. i. P. vulgare. 



Lower surface of the leaf densely scaly ; plant grayish. 2. P. polypodioides^ 



1. Polypodium vulgare L. POLYPODY. (I. F. f. 71.) Rootstock widely 

 creeping, densely covered with cinnamon-colored scales. Stipes light-colored, gla- 

 brous, 5-15 cm. long ; leaves ovate-oblong or narrowly oblong in outline, sub- 

 coriaceous, evergreen, glabrous on both surfaces, 7-25 cm. long, 2.5-4.5 cm. wide, 

 cut nearly to the rachis into entire or slightly toothed, obtuse or subacute, linear 

 or linear-oblong segments ; sori large, borne about midway between the midrib 

 and the margins of the segments ; veins free. On rocks or rocky banks, almost 

 throughout N. Am. , Asia and Europe. Forms with the ends of the segments enlarged, 

 somewhat palmately lobed, and the upper crested are known as var. cristatum. 

 Forms with the segments broad and deeply pinnatifid are called var. Cambricum. 



2. Polypodium polypodioides (L.) A. S. Hitchcock. (I. F. f. 72.) Rootstock 

 widely creeping, woody, covered with small brown scales. Stipes densely scaly, 2.5- 

 4.5 cm. long ; leaves oblong-lanceolate in outline, acute, coriaceous, evergreen, 3-15 

 cm. long, 2.5-4 cm. wide, cut very nearly or quite to the rachis into entire oblong 

 or linear-oblong obtuse segments, glabrous or nearly so on the upper surface, the 

 lower densely covered with gray peltate scales with darker centres, as are also the 

 rachises ; veins indistinct, unconnected, and usually once forked. On trees or 

 rarely on rocks, Pa. to Va. and Fla., west to 111., Mo. and Tex., and throughout 

 tropical America. 



2. NOTHOLAENA R. Br. 



Mostly small rock-loving ferns, with i-3-pinnate or pinnatifid leaves and 

 marginal roundish or oblong sori, which are at first distinct but soon confluent into 

 a narrow band. Indusium none, but the sporanges are sometimes at first covered 

 by the inflexed margin of the leaf. Veins free. Sporanges pedicelled, provided 

 with a vertical transversely bursting ring. Lower surface of the leaf often covered 

 with a white or yellow waxy powder, or in some species with a dense tomentum. 

 [Greek in allusion to the woolly lower surfaces.] About 40 species, of wide dis- 

 tribution, most numerous in America. Besides the following, some 13 others are 

 found in the mountainous portions of the southwestern U. S. 



I. Notholaena dealbata (Pursh) Kunze. (I. F. f. 70.) Rootstock short, chaffy 

 with narrow brown scales. Stipes tufted, wiry, very slender, shining, dark brown, 

 2.5-4.5 cm. long ; leaves triangular-ovate in outline, acute, broadest at the base, 

 2.5-10 cm. long, 3 -pinnate, the rachis black and shining ; pinnae ovate, the lower 

 slender-stalked; ultimate pinnules ovate or obovate, obtuse, lobed, crenate or entire, 

 small, scarcely 2 mm. long, white and powdery on the lower surface. On calcare- 

 ous rocks, Mo. and Kan. to Ariz, and Tex. 



3. ADIANTUM L. 



Graceful ferns of rocky hillsides, woods, and ravines, with much divided leaves 

 and short marginal sori borne on the under side of the reflexed and altered portion 

 of the pinnule, which serves as an indusium. Stipes and branches of the leaves 

 very slender or filiform, polished and shining. [Name ancient.] A genus of 80 or 

 90 species, mostly of tropical America. 



Leaves 2-pinnate, ovate-lanceolate in outline. i. A. Capillus-Veneris. 



Leaves dichotomously forked with pinnate branches. 2. A. pedatum. 



i. Adiantum Caplllus-Veneris L. VENUS-HAIR FERN. (I. F. f. 59.) Root- 

 stock creeping, rather slender, chaffy with light-brown scales. Stipes very slender, 

 black or nearly so, shining, 7-22 cm. long; leaves ovate-lanceolate in outline, bi- 



