FILICES. 669 



Order EQUISETACE^. 



EQUISETUM, L. 



E. robustum, A. Braun. Stem tall (2^-4'' high), stout, simple; the 

 ridges rougliened by a single row of tubercles ; sheaths short, appressed, 

 with a black girdle above the base, and about forty 3-keeled ovate-subulate 

 deciduous teeth. — Banks of the Chattahoochee River, Georgia, and west- 

 ward. 



Order FILICES. 



POLYPODIUM, L. 



P. pectinatum, I>. Stipe erect from a stout rootstock, smoothish (2'- 

 6' long) ; frond 1° -2° long, broadly lanceolate, attenuate at each end, deeply 

 pinnatifid ; pinnae very numerous, alternate, linear-lanceolate, obtuse, mostly 

 entire; sori in two rows. — On trees. East Florida (Miss Reynolds, Garher). 



P. Swartzii, Baker. Rootstock verj' slender, long and climbing ; fronds 

 single, or 2-3 together, 4' or 5' long, lanceolate, mostly obtuse, narrowed at 

 base into the short stipe, the margins wavj', entire ; sori in a single row on 

 the free veinlets. (P. serpens, Swartz.) — Key Largo, South Florida ( Curtiss), 

 climbing on low bushes. 



T^NITIS, Swartz. 



Sori linear, continuous or interrupted, central or intramarginal. — Veins 

 reticulate. 



T. lanceolata, R.Br. Rootstock thick, creeping; frond 6'- 12' long, 

 lanceolate, entire, narrowed at base into the short smooth stipe ; sori intra- 

 marginal along the upper part of the frond. — On trees, Rhoda Key, South 

 Florida {Curtiss). 



PTERIS, L. 



P. serrulata, L. f. Like P. Cretica, L., but the frond bipinnatifid, the 

 numerous divisions narrower, and the rachis broadly winged. — On walls, 

 Charleston. Probably introduced. 



CERATOPTERIS, Brongn. 



Son on 2 or 3 veins which are parallel with the midrib and margins of the 

 frond, the fruit-dots sessile, roundish, the involucre formed by the inflexed 

 margins of the frond which meet at the midrib. 



C. thalictroides, Brongn. Floating ; stipes thick, with large air-cells ; 

 fronds tender, the sterile ones ovate in outline, broadly 3-lobed or 3-parted, 

 or at length bipinnatifid, the margins wavy or bluntly lobed ; the fertile ones 

 2-3 pinnate, with linear divisions. — Head-waters of the St. John's (Curtiss). 



