496 FERN FAMILY. 



lower pair turned obliquely forwards ; secondary divisions crowded, ob- 

 long, obtuse, entire ; fruit dots all near the margin. 



P. hexagon6ptera, Fee. Common N. and S. ; larger than the last, 

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

 pinnae 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 wing- 



less. 



P. Drydpteris, Fee. Common N.. ; fronds broadly triangular, 4'-6' 

 wide, smooth ; the three primary divisions triangular, once or twice pin- 

 nate with oblong, obtuse, entire, or toothed lobes ; fruit dots near the 

 margin. 



16. ASPIDITJM, SHIELD FERN. (Greek for a little shield, refer- 

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

 world. (Lessons, Figs. 502-504.) 



§ 1. Nbphk6bium or Drt6ptebis. Indusium round-kidney-shaped or 

 nearly circular, with a narrow cleft from the lower side almost to the 

 center. 



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

 pinnate; pinnae simply pinnatifid, with mostly entire, obtuse lobes; in- 

 dusium small. 



■<- Bootstoek creeping, slender, nearly naked, and bearing scattered fronds ; 

 veins free, simple, or once forked; common in bogs and low grounds. 



A. Thelypteris, Swartz. 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 ob- 

 long, fruiting ones seeming acute from the revolute margins ; veins mostly 

 forked ; fruit dots confluent when ripe ; indusium smooth ; N. and S. 



A. Noveborace'nse, Swartz. 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 ; indu- 

 sium slightly glandular. N. Car., N". and W. ; common N. 



■i- *- Bootstoek oblique or erect, stouter, bearing the fronds in a crown ; 

 veins simple, free, or the lower ones of contiguous lobes united ; indu- 

 sium hairy. 



A. patens, Swartz. Low, shady grounds, Fla. and W. ; fronds l°-2° 

 high, sparsely pubescent, ovate-oblong ; pinnae 3'-6' long, £' wide, numer- 

 ous, lanceolate from a broad base, lowest pairs a little smaller ; divisions 

 oblong, slightly falcate, obtuse, or acutish ; veins entirely free ; indusium 

 slightly 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. 



■4- Fronds imperfectly evergreen, once-pinnate with deeply pinnatifid 

 pinnoe, or nearly twice pinnate ; fruit dots not close to the margin ; in- 

 dusium rather large, flat, smooth, persistent. 



A. Goldianum, Hook. Rich, moist woods, Conn., to Ky., and N. ; 

 fronds broadly ovate, 2°-4° high, 9'-12' wide ; pinnae oblong-lanceolate, 

 broadest about the middle, parted to the midrib ; divisions very numer- 

 ous, nearly 1' long, somewhat scythe-shaped, rather acute, serrate With 

 incurved teeth ; fruit dots very near the midvein. 



