466 POLYPODIACEAE. 



Rootstocks erect, solitary, or in masses. Petioles tufted, unarmed, erect, 

 woody, 1-6.5 dm. long, flattish, channeled; blades leathery, 1-3 m. long, 3-4.5 

 dm. wide; pinnae 10 pairs or more, close or distant, the venation somewhat 

 oblique to the midvein; sporanges confined to the upper half or third of the 

 leaf -blade, or all segments spore-bearing, or all without spores; segregate of 

 corpuscles covering sporanges sausage-shaped. 



About fresh-water pools and in sink-holes, Andros, New Providence : — Florida ; 

 Bermuda ; West Indies and continental tropical America. Giant Fern. 



Young plants collected by Percy Wilson on Cat Island (7186), show that one or 

 the other of these Acrostichums grows on that island. 



2. VITTARIA J. E. Smith, Mem. Acad. Turin, 5: 413. 1793. 



Usually epiphytic ferns with narrowly linear, grass-like, entire leaves, the 

 linear sori continuous in a groove along each margin, without indusia. Lateral 

 veins obscure, forming a row of areoles on each side of the midvein. [Latin, 

 ribbon-like.] About 40 species, widely distributed in tropical and subtropical 

 regions. Type species: Pteris lineata L. 



1. Vittaria lineata (L.) Sw. in Journ. Bot. Schrad. 1800- : 72. 1801. 



Pteris lineata L. Sp. PI. 1073. 1853. 



Leaves usually numerous, drooping, smooth, shining, tufted on trees, 1-9 

 dm. long, 2-3 mm. wide, the rootstock short, branched, scaly. 



On palmettos, Andros, New Providence : — Florida ; West Indies and continental 

 tropical America. Grass-fern. Shoestring-fern. 



3. PAIiTONIUM Presl, Epim. 156. 1849. 



Epiphytic ferns, with short-creeping rootstocks and narrow entire leaves, 

 the venation reticulated. Sori linear, submarginal, continuous or interrupted, 

 without indusia. [Greek, like a javelin.] Two known species, the following 

 typical one, the other of southern China. 



1. Paltonium lanceolatum (L.) Presl, Epim. 156. 1849. 



Pterin lanceolata L. Sp. PI. 1073. 1753. 



Taenitis lanceolata Kaulf. Enum. 130. 1824. 



Cheilo gramma lanceolata Maxon, Proe. U. S. Nat. Mus. 23: 630. 1901. 



Eootstock short. Leaves tufted, narrowly linear-oblong, glabrous, sub- 

 coriaceous, 1.5-4 dm. long, 0.8-3 cm. wide, tapering to both ends, entire, the 

 midvein prominent, the lateral venation obscure. Sporanges in a continuous or 

 interrupted marginal row above the middle of the leaf, often only near the apex. 



On trees in coppices. Great Bahama, Andros, New Providence : — Florida ; Ja- 

 maica : Cuba to St. Thomas ; St. Eustatius ; Guadaloupe to Barbadoes ; Central Amer- 

 ica. Narrow-lea-s-ed Brake. 



4. PTERIS L. Sp. PI. 1073. 1753. 



Large, mostly coarse ferns, growing in open sunny places, with variously 

 divided leaves, and marginal linear continuous sori which occupy a slender or 

 filiform receptacle, connecting the tips of free veins. Indusium double, the 

 outer one conspicuous, membranous, formed of the reflexed margin of the leaf, 

 the inner one delicate and obscure. Stipes continuous vriih the rootstock. 

 [Greek name for f^ns, from the fancied resemblance of their leaves to the 

 wings of birds.] A few species of wide distribution. Type species: Pteris 

 aquilina L. 



