8 PLOP A. 



pinnate below, simply pinnate above, membranous, commonly drooping, 1.5-6 dm. 

 long, 1-3 dm. wide at the base; pinnules and upper pinnae wedge-obovate or 

 rhomboid, rather Long-stalked, glabrous, the upper margin rounded and more or 

 less incised, crenate or dentate-serrate, except where it is recurved to form the in- 

 dusia. In ravines, Ya. to Fla., west to Mo., S. Dak. and Cal. Widely distributed. 

 2. Adiantum pedatum L. Maiden-hair Fern. (I. F. f. 60.) Rootstock 

 slender, creeping, chaffy, rooting along its whole length. Stipes 2-4.5 dm. l° n g> 

 dark chestnut-brown, polished and shining, dichotomously forked at the summit; 

 leaves obliquely orbicular in outline, 2-4.5 dm. broad, the pinnae arising from the 

 upper sides of the two branches of the stipe, somewhat radiately arranged, the 

 larger ones 1.5-2.5 dm. long, 2.5-5 cm - wide; pinnules oblong, triangular- 

 oblong, or the terminal one fan-shaped, short-stalked, the lower margin entire and 

 slightly curved, the upper margin cleft, Lobed or dentate, bearing the Linear-oblong, 

 often short sori. In woods, N. S. to Br. Col., south to Ga., Ark., Utah and Cal., 

 in Alaska and W. Asia. 



4. PTERIDIUM Scop. 



Large, mostly coarse ferns, growing in open sunny places, with variously di- 

 vided leaves, and marginal linear continuous sori which occupy a slender or fili- 

 form receptacle, connecting the tips of free veins. Indusium membranous, formed 

 of the reflexed margin of the leaf. Stipes continuous with the rootstock. [Greek 

 name for ferns, from the fancied resemblance of their leaves to the wings of birds.] 

 About 100 species of wide distribution, mostly of warm and tropical regions. 



I. P. aquilinum (L.) Kuhn. Brake. Bracken. (I. F. f. 61.) Rootstock 

 stout, woody, horizontal. Stipes 3-6 dm. long, straw-colored or brownish; leaves 

 6-12 dm. long, 3-9 dm. wide, usually glabrous, ternate, the three branches each 

 bipinnate; upper pinnules undivided, the lower more or less pinnatifid. In sunny 

 places, distributed over nearly the whole of N. Am. [P/eris aquilina L.] 



P. aquilinum latiiisculum (Desv:) Underw. Pinnules linear and entire, or with the 

 segments less crowded and the terminal lobe attenuate, narrow and entire. In sandy 

 soil, N. J. to Fla. and Tex. (P. aquilinum pseudocaudatum Clute.) 



5. CRYPTOGRAMMA R. Br. Rock-brake. 



Light green, alpine and arctic ferns with leaves of two kinds, the segments of 

 the sterile much broader than those of the fertile, the sporanges in oblong or 

 roundish sori, which are at length confluent and cover the backs of the fertile pin- 

 nules. Indusium formed of the somewhat altered margin of the pinnule, at first 

 reflexed to the midrib, so that the segments appear pod-like, at length opening out \ 

 flat. Sporanges borne at or near the ends of unconnected veins. [Greek, in allu- 

 sion to the hidden sporanges.] Two species. 



1. Cryptogramma acrostichoides R. Br. (I. F. f. 62.) Rootstock stout, short, 

 chaffy. Stipes slender, densely tufted, straw-colored, 5— 1 5 cm. long, chaffy below; 

 Leaves ovate or ovate-lanceolate in outline, thin, glabrous, 2-3 -pinnate, the sterile 

 shorter than the fertile, their ultimate segments and pinnules crowded, ovate, 



blong or obovate, obtuse, crenate or slightly incised; fertile leaves with linear or i 

 near-oblong segments 6-12 mm. long, 2 mm. or less wide, the margins involute to ] 

 the midrib at first, expanded at maturity and exposing the light brown sporanges. 1 

 Forming dense patches among rocks, Lab. and Hudson Bay to Alaska, south to 

 Lakes Huron and Superior, Colo., and Cal. 



2. Cryptogramma Stelleri (Gmel.) Prantl. (I. F. f. 63.) Rootstock slender, 

 creeping, threadlike, somewhat scaly. Stipes scattered, 5-8 cm. long, straw-col- 

 on d or pale brown, slightly chaffy below; leaves thin-membranous, ovate in out-, 

 line, 5 13 cm. Ion-. 2.5-5 cm - W1,ll '< 2-3-pinnate or pinnatifid above, the fertile 

 taller than the sterile and with narrower pinnules and segments; pinnre lanceolate- 

 deltoid, cut to the ra< his into a few blunt or subacute slightly lobed or entire seg- 



indusium broad, continuous; veins of the fertile leaves mostly only one- 

 forked, ever y where apparent and conspicuous. On rocks, preferring limestone/ 

 Lab. to Br. CoL, south to Ma>s., Peon., Iowa and Colo. Also in Asia. JPe/laeo 

 Stelleri Watt. j 





