132 OUR NATIVE FERNS AND THEIR ALLIES. 



4. L. Inundatum L. Stems creeping horizontally or arch- 

 ing, about 4' long, simple, or once or twice forking, slender, i" 

 or less in diameter, roots produced toward the end of the 

 annual growth ; leaves linear-lanceolate, entire, acute, curved 

 upward ; those of the peduncles straight, entire, more slender, 

 and tapering ; peduncles 2" — 3i' long or the strobiles sessile ; 

 strobiles 4" — \\' long; sporophylls triangular, usually entire, 

 or sometimes toothed just above the base, then somewhat con- 

 tracted ; sporangia subglobose. Pennsylvania and Illinois, 

 northward and westward to British Columbia and Alaska. 



Var. Bigelovii Tuck. Plant larger and more abundantly 

 branching, with more slender stems and slightly longer leaves, 

 which are entire or toothed. New England to Nova Scotia. 



5. L. adpressum (Chapm.) Lloyd & Underw. Stems 

 prostrate and frequently rooting or slightly arching and root- 

 ing toward the end, 7' — 16' long, simple or occasionally pin- 

 nately branching, thick (about ij" in diameter) ; leaves thicker 

 and more rigid than in the last, lanceolate-acuminate, upwardly 

 curving, the margin irregularly toothed, the teeth often com- 

 pound below the middle of the leaf; peduncles 4' — 10' long, 

 usually tall, slender, leafy with more or less appressed subulate- 

 toothed leaves below and similar entire leaves above ; strobiles 

 narrow, about \\" in diameter and f — 3' long; sporophylls 3" 

 long with a broad base, suddenly contracted above into a nar- 

 row subulate apex, usually more or less toothed near the 

 base ; sporangia subglobose. Massachusetts to Florida and 

 Louisiana. 



\ X sporophylls longer (4" — 5"), usually much-toothed. 



6. L. pinnatum (Chapm.) Lloyd & Underw. Stems pin- 

 nately branching, elongate (8' — 12') and very slender (i" — i") 

 with five gum canals, and evident dorsiventral character, no 

 air-spaces ; leaves (4" X V) thin, linear-lanceolate, slightly 

 curved, long-tootlied, those of the upper side smaller, all some- 

 what contracted at the base ; those of the peduncles similar but 

 more gradually tapering to the apex; peduncles 10' — 16' long, 

 slender, very leafy; strobiles i' — S' long, 2j" thick, with spread- 

 ing sporophylls, similar to the peduncular leaves, but longer 



