68 Our Native Ferns. 



r Sporangia in close distichous spikes, . . . XXVIII. 



■ I Sporangia in copiously branching panicles, XXVII. 



{Sporangia cohering in simple spikes; veins re- 

 ticulated, XXX. 

 Sporangia mostly panicled ; veins free. . . . XXXI. 



SYSTEMATIC DESCRIPTIONS OF GENERA AND 

 SPECIES. 



XoTE. — Species peculiar to North America are indicated by au asterisk (*). Bomau 

 uuDierals following the species indicate geographical sub-divisions. (See page 22.) 



I. ACROSTICHUM, L. 



Sporangia spread over the whole surface of the frond or upper 

 pinnae, or occasionally over both surfaces. Venation and cutting 

 various (in our species simply pinnate). 



I CHRYSODIUM. 



I. A. aureum, L. Stipes t" — 2° long, tufted, strong, erect, 

 glossy; fronds 2° — 6° long, 1° — 2° broad, upper pinnae fertile- 

 slightly smaller than the barren oi:es; texture coriaceous; areolas 

 small, copious, without free veinlets. Fla. VL 



H. POLYPODIUM, L. Foi^ypoDY. 

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

 midrib, or irregularly scattered. Stipes articulated to rhizoma. 

 J I. EUPOLYPODIUM. I'eiiis free ; fronds (in our species) 



pinnate. 



* Sori large. 



1. P. vulgare, L. Stipes 2' — 4' long, firm, erect ; fronds 4' — 

 10' long, i' — 3' broad cut nearly or quite to the rachis into entire 

 or slightly toothed, usually blunt pinnae ; veins once or twice 

 forked. Larger fronds with their pinnae sharply serrated and long 

 pointed form the var. occidentale, Hook. N. Eng. westward to 

 Ore. and southward to Ala. III. 



2. P. falcatum*, Kellogg. ■ Stipes 5' — 8' long, stramineous ; 

 fronds 12' — 13' long, 4' — 8' broad; pinnae numerous, tapering to 

 a slender point, sharply serrate; sori neaiest the midrib ; veins 

 with 2—4 veinlets. Cal. to W. T. IV. 



^*Sori smaller, often minute. 



3. P. plumula, H. B. K. Stipes i' — 4' long, black, slender; 

 fronds narrowly lanceolate, 9' — 18' long, i' — 2' broad; pinnae nu- 

 merous, narrow, entire, blunt, lower gradually reduced; surfaces 

 naked except the black wirv rachis; veinlets forked, obscure. 

 Fla. VI. 



