ORDER 159. FILICES. 421 



1 N. NITEA. Very delicate, 612', bright green above, covered with a dense white pow- 



der beneath ; frond bipinnate; pinnae roundish, top one lobed: stipe black. Mex. 



2 N. ECKLOMANA. Rare and beautiful, clothed in white wool-like scales, bipinnate, 



pinnae ovate, remote, pinnulae pinnatifid, oblong, segments roundish. South Africa. 



15. ONOCLEA, L. SENSITIVE FERN. Fronds scattered, net- veined, 

 the sterile broad, the fertile contracted and panicled, its convolute segments 

 berry-like, enclosing the sori, which are otherwise nearly naked. 



O. seiisibilis L. Fronds 1 2f, common in low grounds, very sensitive to frost. The 

 fertile dark-brown in color. Sterile fronds deeply pinnatifid, with few oblong entire 

 or lobed pinme, the upper confluent. July. 



ft. obtugilofta. Fertile frond partially metamorphosed, the segments partly revo- 

 lute on the fruit. Wendell, Mass. (Mrs. Piper), to N. Y. and Penn. 



16. STRUTHIOPTERIS, Willd. OSTRICH FERN. Fronds clustered, 

 the sterile bipinnatifid, fork-veined, fertile much contracted, brown, with 

 the pinnae revolute into a necklace form, enclosing the sori, which are 

 otherwise destitute of an indusium. 



S. Germ mica Willd. Sterile fronds in a circular clump, 3 5f; pinnae numerous, 

 long and crowded, with numerous oblong segments ; fertile fronds much smaller, 

 their crowded pinnae 1 2' long, appearing later in the season. 



17. ALLOSORUS, Bernh. Fronds small, 2-3-pinnate, fork-veined; 

 the fertile some contracted, margins of the leaflets reflexed and meeting 

 over the confluent sori, but soon opening. 



A. acrostielioides Spr. Fronds in tufts, bipinnate, 3 6', pale green with whitish 

 stipes ; eeg. oblong, the sterile crenate, the fertile entire, petiolulate, 2 3" long. Islo 

 Royal, in L. Superior (Prof. Porter), W. to Washington Terr. (Rev. Mr. Gray). 



18. LOMARIA, Willd. Fronds clustered, of 2 forms, the fruitful con- 

 tracted. Sori marginal, linear, continuous ; indusium linear, scarious, the 

 reflexed edge of the frond, opening toward the mid-vein. 



1 Li. SPICANT. Fronds pinnate, long, and narrow, the fertile nearly solitary in the midst 



of the numerous sterile ones, and twice as tall (2 3f) as they ; stipe purple, polished. 

 Europe, Oregon. Very elegant. (Blechnum boreale.) 



2 Ij. GIBBA. Fronds oblong-lanceolate, pinnate, pinnae linear-falcate, 13', their broad 



bases almost confluent. 



3 L. CILIATELLA. Fronds oval to oblong; pinnae oblong, slightly lobed, truncate at 



apex, ciliolatc-spinescent with the projecting veins. 



19. FTERIS, L. BRAKE. Sori borne on the ends of the veins forming 

 a marginal line or band, covered with the membranous, reflected edge of 

 the frond. Fronds once to thrice pinnate, or decompound. 



| PTERIS proper. Sori a mere line. Stipes greenish or pale. . .(x) 



| PELL^EA. Sori forming a broad band. Stipes purple or brown. . . (y) 



x Frond triangular, twice or thrice pinnate, lowest pinnae long-stalked No. 1 



x Frond pedately pinnate, the pinnae few and long Nos. 2, 3 



x Frond pedately bipinnatifid, the pinnae numerous No. 4 



X Frond simply pinnate, with numerous long pinnae No. 5 



y Frond pedate and pinnatifld, as broad as long. 5-angled. t No. 



y Fronds pinnate, pinnie few, the lower again divided. Native NOP. 7, 8 



y Fronds pimply pinnate, or completely tripinnate. Cultivated Nos. 911 



