FILICES. (FERNS.) 627 



obovate, sessile or adnate-decurrent, the margin reflexed forming a continuous 

 somewhat membranaceous involucre. French Broad River, North Carolina 

 and Tennessee, and southwest ward. Frond 6' -12' long. Stipe and rachis 

 whitish with long paleaceous hairs. 



4. C. microphylla, Swartz. Stipe dark brown, from a short rootstock, 

 smoothish ; frond smooth, broadly lanceolate, 2-3 pinnatifid, 3' -9' long; 

 pinnre lanceolate from a broader base; pinnules linear-oblong, obtuse, entire, 

 or the lower ones pinnatifid ; involucre pale, narrow. Islands near the mouth 

 of the St. John's (Curtiss). Frond 1 or less long. 



8. ADIANTUM, L. MAIDENHAIR. 



Indusium orbicular or transversely elongated, formed of a reflexed and al- 

 tered portion of the margin of the frond, bearing the sporangia on its under 

 side at the ends of the veins. Midrib none or eccentric: veins forking, mostly 

 free. Stipe and rachis commonly black and shining. 



1. A. podatum, L. Stipe long and slender, forked, the spreading and 

 recurved branches bearing on the outer side several slender horizontal pinnate 

 divisions; pinnules numerous, alternate, short-stalked, oblong, entire on the 

 lower side, the upper margin cleft and fruit-bearing. Shady woods, North 

 Carolina, and northward. Stipe 8'- 12' high. The most graceful of all our 

 Ferns. 



2. A. tenerum, Swartz. Frond deltoid, 3- 4-pinuate; pinnules stalked, 

 obliquely rhombic, deciduous, the wedge-shaped base and lower edge entire, 

 the upper edge broadly and shortly lobed, bearing the transverse sori at their 

 tips. East Florida (Feay, etc.). Fern l-3 high, the black stipe and ra- 

 chis smooth and glossy. 



3. A. Capillus-Veneris, L. Frond ovate-lanceolate, 2-3-pinuate; 

 pinnules very delicate, oblique, broadly wedge-shaped or sometimes rhomboid, 

 rather long-stalked, the upper margin deeply incised and fruit-bearing or 

 sterile and dentate ; stipe slender, ebeneous ; rachis almost capillary, flexuous. 

 Mostly pendent from limestone cliffs, Florida to North Carolina, and west- 

 ward. Fronds l-3 long. 



9. CERATOPTERIS, Brongn. 



Sori 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. 



1. 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). 



10. BLECHNUM, L. 



Sporangia on a transverse elongated receptacle parallel to the midrib, com- 

 bining the veins near their bases. Indusium fixed by its outer margin, 

 opening inward. Veins of the sterile fronds free. Fronds simple or pinnate 



