518 Key to the System of 



2161. Frond-segments flaccid, hardly paler beneath. 



Seldom quite tall, occasionally dwarfed ; fronds almost 

 lanceolar in outline, simply pinnate ; segments sessile, 

 from a broad base mostly linear-lanceolar, rather acute, 

 their base sometimes rather rounded or even slightly 

 bi-lobed, the terminal segment much elongated ; lateral 

 venules very divergent, almost parallel ; spore-caselets 

 placed on a filiform-linear axis. P. longif olia. 



Frond-segments firm, much paler beneath. 



Rather dwarf ; fronds almost lanceolar in outline, simply 

 pinnate ; rhachis as well as the stalk dark- colored and 

 beset with rigid hairlets or narrow scalelets ; segments 

 sessile, nearly semi-lanceolar, often entire and slightly 

 curved upwards, exceptionally at the base bluntly bi- 

 lobed and also throughout more dilated, always beneath 

 greyish-green and without any lustre ; venules concealed ; 

 fruit-cover very narrow; spore-caselets occupying a broad- 

 linear space intra-marginally, arising from the upper 

 portion of venules. (Pellaea falcata.) Figure 145. 



F. falcata. 



2162. Fronds rigid. 



Often very tall; root -stock far - creeping ; fronds ample, 

 broadest towards the base ; segments rather distant and 

 unequal, mostly broad-linear and blunt, somewhat de- 

 current, the terminal segment more elongated, some of 

 the lateral segments much abbreviated, all rather convex 

 and transversely impressed -streaked above, at the margin 

 recurved, beneath often ,beset with hairlets ; spore- 

 caselets placed on a filiform -linear axis. " Brake-fern. " 



P. aquilina. 



Fronds flaccid ... *.. 2163 



2163. Segments of pinnules narrow-lobed. 



Rather tall, glabrous ; fronds ample ; rhaches as well as the 

 stalk rather pale and slight-yellowish, but occasionally 

 dark -brown, smooth ; segments rather approximated, 

 from lanceolar- to broad-linear, blunt, confluent at the 

 base, serrulated towards the summit, the terminal 

 segment somewhat elongated ; venules diverging ; spore- 

 caselets placed on a filiform-linear axis. P. arguta. 



Segments of pinnules broad-lobed 2164 



