ORDER 159. FILICES. 421 



1 N. NIVEA. 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. ECKLONIANA. Rare and beautiful, clothed in white wool-like scales, bipinnate, 



pinnae ovate, remote, pinnuke 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. sensifoilis L. Fronds 1 2f, common in low grounds, very, sensitive to frost. The 

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

 or lobed piunse, the upper confluent. July. 



/3. obttisiloha. 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 bipiunatifid, 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. Germanica 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 12' long, appearing later in the season. 



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

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

 over the confluent sori, but soon opening. 



A. acrostlclioides Spr. Fronds in tufts, bipinnate, 36', pale green with whitish 

 stipes ; seg. oblong, the sterile crenate, the fertile entire, petiolulate, 2 3-" long. Isle 

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



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

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



2 L. 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 ftt 



apex, ciliolate-ppinescent with the projecting veins. 



19. PTERIS, 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 1'ne. Stipes greenish or pale.. . (x) 



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



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



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



x Frond pedately bipinnatifid. the pinnte numerous No. 4 



x Frond simply pinnate, with numerous long pinme No. 5 



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



y Fronds pinnate, p nine few, the lower again divided. Native Nos. 7, 8 



y Fronds simply pinnate, or completely tripiunate. Cultivated Nos. 9 11 



