86 Our Native Ferns. 



17. A. thelypteroides, Michx. Stipes long, erect, stramineous; 

 fronds 1° — 2° long, 6' — 12' broad, bipinnatifid ; pinnae linear-lan- 

 ceolate; segments crowded, oblong, minutely toothed ; sori 5— 6 

 pairs to each segment, slightly curved, the lower ones often 

 double. N. Eng. to Ky. and 111. III. 



18. A. filix-foemina, Bernh. (Lady-fern). Stipes tufted, 6' 

 — 12' long, stramineous or brownish ; fronds delicate, \\° — 3° long, 

 broadly oblong-ovate, bipinnate ; pinnae 4' — 8' long, lanceolate ; 

 pinnules oblong-lanceolate, pointed, more or less pinnately in- 

 cised or serrate, distinct or confluent on the secondary rachises by 

 a very narrow and inconspicuous margin ; sori short ; indusium 

 straight or variously curved. Small starved specimens growing in 

 mountainous places form the var. exile, D. C. Eaton, often fruit- 

 ing when 3'— 6' high. Eastern U. S., Cal., Nev., Utah, Ariz. III. 



Var. ANGUSTUM, D. C. Eaton. Fronds 1° — 3° high, rather 

 rigid, narrow in outline, nearly bipinnate; pinnae obliquely ascend- 

 ing or curved upward, narrowly lanceolate; segments crowded, 

 crenate, or serrate; sori usually abundant, straight or curved. 

 (Var. Michauxii, Mett). N. Eng. to Ind., Utah, Cal. III. 



Var. LATIFOLIUM, Hook. Fronds 2' — 3° high, oblong-lanceo- 

 late, nearly bipinnate; pinnas 3' — 4' long, oblong-linear, with a 

 narrowly winged secondary rachis ; pinnules broadly ovate and 

 foliaceous, simply or doubly serrate ; sori nearer the midvein than 

 the margin ; indusia straight or curved, the basal ones often horse- 

 shoe-shaped. Ore., Pa. III. 



Var. CYCLOSORUM, Rupr. Fronds very large, often 5° high, and 

 18' — 20' broad, bipinnate — tripinnatifid ; pinnules often i' long, 

 oblong-lanceolate, pinnatifidly incised, or nearly again pinnate ; 

 sori roundish ; indusium very short. Vt., Ore., and northward. III. 



XVI. SCOLOPENDRIUM, Sm. Hart's-tongue. 



Sori linear elongated, almost at right angles to the midvein, 

 contiguous by twos, one on the upper side of one veinlet, and the 

 next on the lower side the next superior veinlet, thus appearing 

 to have a double indusium opening along the middle. 



I. S. vulgare, Sm. Stipes 2' — 6' long, fibrillose below ; fronds 

 oblong-lanceolate from an auricled-heart-shaped base, entire or 

 undulate, 7'— 18' long, i'— 2' wide, bright green. Central N. Y., 

 Canada and Tenn. Rare and local. II. 



XVII. CAMPTOSORUS, Link. Walking-leaf. 



Sori oblong or linear, irregularly scattered on either side of the 

 reticulated veins of the simple frond, those next the midrib single, 



