POL YPOD I A CEM. o I 



Sori partly oblique and partly parallel to the midrib ; leaf simple, 



tapering to a point XXI. Camptosorus, p. io8 



22. Veins free . . 23 



Veins reticulate .... . . XVIII. Woodwardia, p. 102 



' 23. Ijidusium near the margin ; sporophyll much contracted. 



XVI. Struthiopteris, p. 101 

 Indusium remote from the margin ; leaves nearly uniform. 



XVn. Blechnum, p. 102 

 24. Sori on the upper side of a veinlet, rarely on both sides. 



XIX. ASPLENIUM, p. 103 



Sori confluent in pairs, with an apparently double indusium opening in 

 the middle XX. Phyllitis, p. 107 



I. ACROSTICHUM L. 



Sporangia spread over the whole surface of the frond or upper 

 pinnae, or occasionally over both surfaces. Venation anasto- 

 mosing (our species simply pinnate). Name from Gr. aKpoi, 

 the summit, and arixoi, a row. A tropical genus containing 

 about five species as here limited. 



1. A. aureum L. Rootstocks erect, solitary or in masses; 

 stipes cespitose, erect ligneous, ii° — 2i° long, flattish-channelled, 

 with two or three alternate pairs of black indurated spurs, 

 fronds erect, stiff, coriaceous, glossy, light green ; 3° — 4° long; 

 1° — ii° wide; pinnae 12 or more pairs, rather distant; sporangia 

 confined to the upper half or third of the frond ; venation fine, 

 oblique to the margin. Southern Florida. 



2. A. lomarioldes Jenman. Rootstocks erect massive; 

 stipes cespitose, erect, subfleshy, ii° — 2^° long, longitudinally 

 ribbed, subangular ; fronds erect-spreading, 3° — 4° high, 1° — 2° 

 wide, slightly reduced at base, suddenly reduced at the apex ; 

 pinnae patent, close or crowded, 25 — 30 pairs, the face turned 

 upward and transverse with the rachis ; sporangia covering all 

 the pinnae of fertile fronds ; areolae very fine, directed toward 

 the margin. South Florida. 



II. POLYPODIUM L. 



Sori round, naked, dorsal, in one or more rows each side of 

 midrib, or irregularly scattered. Stipes articulated to root- 



