FILICES. 669 



ORDER EQUISETACE^E. 



EQUISETUM, L. 



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

 ridges roughened 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, L. Stipe erect from a stout rootstock, smoothish (2' - 

 6' long) ; frond l-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, Garber). 



P. Swartzii, Baker. Rootstock very 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 wavy, entire ; sori in a single row on 

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

 climbing on low bushes. 



T.EJNITIS, 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). 



