686 FiLTCES. (ferns.) 



12. PHEGOPTERIS, Fee. Beech Fern. 



Fniit-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 <p-ny6s, an oak or heech, and inepU,fern.) 



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



1. P. polypodioides, Fee. 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. — Eootstock slender, creeping, bear- 

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



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

 /on^ (7-12' broad}, slightly pubescent and often finely glandular beneath; 

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

 the very large lowest pinnce elongated and pinnately lohed, 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. — Rather 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 icidely 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 pinna 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, 

 aa-Ki^iov, a small shield, from the shape of the indusium.) 



§ 1. DRY6PTERIS. 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. Thel^pteris, 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.) 



