686 FILICES. (FERNS.) 



12. PHEGOPTERIS, Fee. BEECH FERN. 



Fruit-dots small, round, naked (no indusium), borne on the back of the veins 

 below the apex. Stipe continuous with the rootstock. Our species have free 

 veins and bright green membranaceous fronds, decaying in early autumn. 

 (Name composed of <f>fiy6s, an oak or beech, and Trrepis, fern.) 



* Fronds twice pinnatifid ; pinnce all sessile, adnate to the winged rhachis. 



1. P. polypodioides, Fe'e. Fronds triangular, longer than broad (4-9' 

 long), hairy on the veins, especially beneath ; pinnae linear-lanceolate, the low- 

 est pair dejlexed and standing forward ; their divisions oblong, obtuse, entire, 

 the basal decurrent upon the main rhachis ; fruit-dots all near the margin. 

 Damp woods ; common northward. July. Kootstock slender, creeping, bear- 

 ing a few distant slender stalks, rather longer than the fronds. (Eu.) 



2. P. hexagondptera, Fe'e. Fronds triangular, usually broader than 

 long (7-12' broad), slightly pubescent and often finely glandular beneath; 

 pinnae lanceolate ; upper segments oblong, obtuse, toothed or entire, those of 

 the very large lowest pinnce elongated and pinnately lobed, basal ones very much 

 decurrent and forming a continuous many -angled wing along the main rha- 

 chis ; fruit-dots near the margin ; some also between the sinus and the mid- 

 rib. Eather open woods, New Eng. to Minn., and southward ; common. July. 



Larger and broader than the last, which it often closely resembles. 



* * Fronds ternate, the three divisions petioled ; rhachis wingless. 



3. P. Dryopteris, Fee. Fronds smooth, broadly triangular (4 - 6' wide) ; 

 the three triangular primary divisions all widely spreading, 1 - 2-pinnate ; seg- 

 ments oblong, obtuse, entire or toothed ; fruit-dots near the margin. Rocky 

 woods; common northward. July. (Eu.) 



4. P. calcarea, Fee. Fronds minutely glandular and somewhat rigid, 

 the lateral divisions ascending ; lowest inferior pinnae of the lateral divisions 

 smaller in proportion than in the last species, which it otherwise closely re- 

 sembles. Iowa and Minn. ; rare. July. (Eu.) 



13. ASPIDIUM, Swartz. SHIELD FERN. WOOD FERN. (PI. 19.) 



Fruit-dots round, borne on the back or rarely at the apex of the veins. In- 

 dusium covering the sporangia, flat or flattish, scarious, orbicular and peltate 

 at the centre, or round-kidney-shaped and fixed either centrally or by the sinus, 

 opening all round the margin. Stipe continuous (not articulated) with the 

 rootstock. Our species have free veins and 1 - 3-pinnate fronds. (Name, 

 dffiriSiov, a small shield, from the shape of the indusium.) 



1. DRYOPTERIS. Indusium reniform, or orbicular with a narrow sinus. 

 * Veins simple or simply forked and straight; fronds annual, decaying in au- 

 tumn, the stalks and slender creeping rootstocks nearly naked. 



1. A. Thelypteris, Swartz. Fronds pinnate, lanceolate in outline ; pin- 

 nae horizontal or slightly recurved, linear-lanceolate, deeply pinnatifid, the low- 

 est pairs scarcely smaller ; lobes oblong, entire, obtuse or appearing acute when 

 in fruit from the strongly revolute margins ; veins mostly forked, bearing the (soon 

 confluent) fruit-dots near their middle; indusium minute, smooth and naked. 



Marshes ; common. Aug. Stalk 1 long or more, usually longer than the 

 frond, which is of thicker texture than the next, and slightly downy. (Eu.) 



