368 FERN FAMILY. 



* Fronds twice pinnatifid: the sessile pinnae mostly forming an irregular and 



many-angled wing along the rltachis. 



P. polypodiold.es, formerly POLYPODIUM PnEG6pTERis. Common N. : 

 fronds 4' -9' long, longer than broad, triangular-ovate, slightly hairy beneath; 

 pinnae lanceolate, the lower pair turned obliquely forwards ; secondary divisions 

 crowded, oblong, obtuse, entire; fruit-dots all near the margin. 



P. hexagon6ptera. Common N. & S. : larger than the last, which it 

 much resembles, but the frond is broader than long ; lowest pinna much the 

 largest and with elongated and pinnatifid divisions ; fruit-dots not exclusively 

 near the margin. 



* * Fronds with three primary divisions, which are stalked, rhachis wingless. 



P. Dryopteris. Common N. : fronds broadly triangular, 4' -6' wide, 

 smooth ; the three primary divisions triangular, once or twice pinnate with ob- 

 long obtuse entire or toothed lobes ; fruit-dots near the margin. 



15. ASPIDIUM, SHIELD-FERN. (Greek for a little shield, referring to 

 the indusium. ) A very large genus, inhabiting all parts of the world. 



1. NEPHR6DIUM or DRYOPTERIS. Indusium round-kidney-shaped or nearly 



circular with a narrow cleft from the lower side almost to the centre. 

 # Fronds thickish, simply pinnate, the few pinnae entire or nearly so. 



A. Siebbldii. Cult, from Japan : fronds coriaceous, smooth, about 1 

 high, with 2-4 pairs of side pinnas, each 4' -6' long and nearly 1' wide, and a 

 terminal one rather larger than the others ; veins with 4-6 free parallel branch- 

 es ; fruit-dots large, scattered in several rows. 



* * Fronds thin, decaying in early autumn (or tender hot-house plants), pinnate : 



pitince simply pinnatifid with, mostly entire obtuse lobes : indusium small. 



+- Rootstock creeping, slender, nearly naked and bearing scattered fronds : veins 

 free, simple or once forked : wild species, common in bogs and low grounds. 



A. Thetypteris. Fronds lanceolate, 10' -18' long, on slender stalks, 

 nearly smooth; pinnae lanceolate, 2' -4' long, about ' wide, spreading or 

 turned down, the lowest pair scarcely shorter ; divisions oblong, fruiting ones 

 seeming acute from the revolute margins ; veins mostly forked ; fruit-dots con- 

 fluent when ripe ; indusium smooth. 



A. Noveboracense. Much like the last, but hairy beneath along the 

 rhachis and veins ; fronds tapering both ways from the middle ; lower pinnae 

 gradually smaller and distant ; lobes flat, the basal ones often larger and incised ; 

 veins rarely forked; fruit-dots distinct; indusium slightly glandular. 



*- - Rootstock oblique or erect, stouter, bearing the fronds in a crown : veins simple, 

 free, or the lower ones of contiguous lobes united: indusium hairy. 



A. patens. Low shady grounds, Florida and W. : fronds l-2 high, 

 sparsely pubescent, ovate-oblong; pinnae 3'-G' long, A' wide, numerous, lance- 

 olate from a broad base, lowest pairs a litile smaller ; divisions oblong, slightly 

 falcate, obtuse or acutish ; veins entirely free ; indusium slightly hairy. 



A. mdlle. Cult, from tropical countries : very much like the last, but ev- 

 erywhere downy or soft-hairy ; pinnse less deeply lobed ; lobes obtuse ; lower 

 veinlets (1 or 2 pairs) uniting with the corresponding ones of contiguous lobes 

 and sending out a ray-like veinlet to the sinus ; indusium very hairy. 



* * * Fronds smooth, from once to thrice pinnate, growing in a crown from a 



stout and chaffy rootstock, and often remaining green through the winter : 

 veins 2 - ^-forked or branching. Wild species of the country. 



*- Fronds imperfectly evergreen, once pinnate with deeply pinnatifid pinnae, or 

 nearly twice pinnate : fruit-dots not close to the margin : indusium rather 

 large, flat, smooth, persistent. 



A. Goldianum. Rich moist woods N. : fronds broadly ovate, 2 - 4 high, 

 9' -12' wide; pinna? oblong-lanceolate, broadest about the middle, parted to the 



