368 FERN FAMILY. 



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



many-angled wing along the rhachis. 



P. polypodioldes, formerly POLYPODIUM PHEGOPTERIS. 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. hexagonoptera. 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 pinnatiild 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 thickiah, simply pinnate, the few pinnae, entire or nearly so. 

 A. Si.eb61d.ii. Cult, from Japan : fronds coriaceous, smooth, about 1 

 high, with 2-4 pairs of side pinnae, 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 : 



pinnce 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 revolutc 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. 



i- *- 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' -6' long, ' 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; pinna? 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 - 4-forked or branching. Wild species of the country. 



-i- Fronds imperfectly evergreen, once pinnate with deeply pinnatifid pinnce, 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; pinnae obloug-lanceolate, broadest about the middle, parted to the 



