POLYPODIUM.] FILICES. 467 



Heaths and pastures in mountain districts ; ascending to nearly 3,000 ft. in 

 the Highlands ; local and rare in Ireland ; frt. July- Aug. Rootstock 

 erect or decumbent, and short stout stipes and rachis bolow scaly. 

 Frond li-2 fo., broadly oblongjanceolate ; pinnae 3-4 in., spreading, sessile, 

 lanceolate, lower smaller more obtuse and distant ; lobes flat, obtuse, 

 entire, costa pubescent ; lower venules forked. Sori near the margins. 

 Involucre membranous. DISTRIB. Europe (excl. Sweden), W. Asia. 



13. POLYPO'DIUM, L. POLYPODY. 



Ferns of various habit. Fronds simple, lobed, pinnatifid or compound. 

 Sori dorsal, globose ; involucre 0. DISTRIB. All regions, but chiefly trop. ; 

 species 390. ETYM. iro\vs and -novs, from the many stipes of some. 



SECTION 1. Polypo'dium proper. Stipes articulate with the rootstoct. 



1. P. >vulgra're, L. ; rootstock creeping densely scaly, fronds alternate 

 pinnatifid, segments linear-oblong obtuse or acute entire crenate-serrate. 

 Walls, banks, tress, &c. ; ascending to 3,400 ft. in Yorkshire ; frt. June- 

 Sept. Rootstock stout ; scales pale brown, lanceolate. Stipes stout, 3-4 in. 

 Frond 6-12 in., linear-oblong or ovate-oblong, coriaceous, naked and gla- 

 brous ; segments ^-3 in. broad ; venules pinnate, tips thickened. Sori 

 large, 1-scriate, terminal on a lateral venule. DISTRIB. Europe, N. and S. 

 Africa, Siberia, Dahuria, Japan, W. Asia, N. America. 



VAR. cam'bricum, L. (sp.) ; segments pinnatifid. 

 SECTION 2. Phearop'teris. Stipes not articulate with the rootstock. 



2. P. Phsgop'teris, L. ; rootstock creeping scaly, fronds alternate 

 pinnate, pinnae pinnatifid, lowest pair deflexed, segments obtuse ciliate. 

 Damp shaded places in mountain districts, from Sussex and Cornwall north- 

 wards ; ascending to nearly 3,500 ft. in the Highlands ; local in Ireland ; 

 frt. June-Aug. Rootstock long, slender ; scales scattered. Stipes 6-9 in., 

 slender, scaly at the base. Frond 6-9 in., subdeltoid, slightly hairy below, 

 rather membranous, pinnate below, pinnatifid above ; pinnae subopposite, 

 elongate, sessile ; lower 2-3 in. ; segments subentire ; venules 6-8 on each 

 side, lower forked, tips thickened. Sori near the margin, dorsal on the 

 venules. DISTRIB. Europe, N. aad W. Asia, N. America. 



3. P. Dryop'teris, L. ; rootstock creeping scaly, fronds alternate del- 

 toid 2-pinnate, pinnae deeply pinnatifid, segments obtuse subcrenate. 



Dry shaded places in mountain districts from S. Wales and Gloucester north- 

 wards ; ascending to 2,700 ft. in the Highlands ; N. of Ireland, very rare ; 

 frt. July-Aug. Rootstock long and slender; scales orange-brown. Stipet 

 very slender, 6-12 in., scaly towards the base. Frond 6-12 in., thin and 

 flaccid, glabrous ; lower pinnse the largest ; lowest segments sometimes free ; 

 venules forked, tips thickened. Sori submarginal, dorsal on the venules. 

 DISTRIB. Europe, N. and W. Asia, Himalaya, N. America. 



Sub-sp. DRYOP'TERIS proper ; frond glabrous flaccid. 



Sub-sp. ROBERTIA'NUM, Ho/m. (sp.) ; rootstock stouter, frond more coria- 

 ceous glandular-pubescent. P. calcareum, Sm. Limestone rocks from 

 Somerset and Bucks to Westmoreland and Durham ; ascending to 1,200 ft. 

 in Northumberland ; absent from Ireland ; extends to Tibet. 



4. P. alpes'tre, Hoppe; rootstock stout oblique, frond oblong-lanceolate 

 2-pinnate, pinnules deeply pinnatifid, lobes toothed. Pseudathyrium, 

 Newin. 



H H 2 



