22 BRITISH FERNS. 



Genus 4. POLYSTICHUM, Roth. 



1. P. Lonchitis. Fronds pinnate, spiny-serrate. 



2. P. aculeatum. Frond bipinnate, rigid; pinnules ovate 



subfalcate, auricled, acute, acutely wedge-shaped at the 

 base, nearly all distinct. 



Var. lobatum. Fronds narrower, pinnules nearly all 

 decurrent. 



3. P. angulare. Fronds bipinnate ; lax ; pinnules oblong or 



ovate subfalcate, auricled, bluntish or acute, obtusely 

 angled at the base, stalked. 



Var. subtripinnatum. Fronds ample lower pinnules 



deeply pinnatifid, otherwise normal. 

 Var. proliferum. Fronds bearing bulbils ; pinnules 

 narrow, acute, deeply pinnatifid, with distant at- 

 tenuate lobes. 



Var. imbricatum. Fronds narrow ; pinnules oblong- 

 obtuse, overlapping. 



Var. alatum. Fronds normal in outline ; pinnules con- 

 nected by a broad wing, which obliterates the stalk. 

 Genus 5. LASTREA, PresL 



1. L. Thelypteris. Fronds pinnate, not glandular ; sori sub- 



marginal on more or less contracted fronds; caudex 

 creeping. 



2. L. montana. Fronds pinnate, covered with sessile glands; 



caudex tufted. 



3. L. Filix-mas. Fronds sub-bipinnate or bipinnate, broadly 



lanceolate ; indusium plain. 



Var. incisa. Larger, pinnules elongate, with deep 



serrated incisions. 

 Var. paleacea. Larger, pinnules truncately-obtuuc, 



entire ; stipes very scaly. 



Var. pumila. Smaller, pinnules contracted, con- 

 _ fluent. 



4. L. i^igida. Fronds bipinnate, without spinulose serra- 



tures, glandular ; indusium fringed with glands. 



5. L. cristata. Fronds narrow linear, pinnate or sub- 



bipinnate, pinnules oblong, with aristate teeth, the pos- 

 terior and anterior ones nearly equal ; scales ovate, pale. 

 Var. uliginosa. Fronds (fertile) narrow linear-lanceo- 

 late, b'ipinnate at the base, pinnules oblong, acute, 

 with aristate teeth, the posterior and anterior ones 

 nearly equal ; sterile fronds as in 5 ; scales ovate, 

 pale. 



