138 FILICES. (true ferns.; 



* Base of the stalk which encloses the bud closed on all sides : sterile division 



more or less fleshy , the cells of the epidermis straight. 

 *- Sterile division usually placed at or above the middle of the plant : frond 



never hairy. 



1. B. Llinaria, L. Plant 4 to 10 inches high, very fleshy : sterile division 

 sessile near tlie middle of the plant, oblong or ovate, once pinnatifid ; pinnae or 

 lobes semilunar from a broadly cuneate base, the sides concave, the outer 

 margin crenate or even incised. — From Colorado (Parry) and New England 

 northward. 



2. B. lanceolatum, Angstr. Plant 2 to 10 inches high, scarcely fleshy : 

 sterile division high up on the plant, sessile, deltoid, once or twice pinnatifid 

 with oblique oblong-lanceolate acute segments. — From Colorado (Brandegee) to 

 New England and in the far North. 



■t- h~ Sterile division placed low down on the plant. 



3. B. Simplex, Hitchcock. Plant smooth, fleshy, 2 to 6 inches high: 

 sterile division short-petioled, varying from simple and roundish-obovate and 2 to 

 3 lines long, to triangular-ovate and deeply 3 to 1-lobed, or even to fully ternate 

 with incised divisions ; segments broadly obovate-cuneate or somewhat lunate : 

 fertile division 1 to 2-pinnate. — Yellowstone Park (Parry) and California ; 

 eastward from Lake Superior to New England. Exceedingly variable, the 

 true form thought to be most nearly represented by 



Var. GOmpositum, Milde. A low alpine form with the sterile segment 

 an inch or less long, ternate, or composed of 3 ovate incised segments. 



4. B. ternatum, Swartz. Plant sparsely hairy, fleshy, 4 to 12 inches 

 high : sterile division long-petioled from near the base of the plant, broadly 

 deltoid, ternate and variously decompound ; ultimate segments from roundish- 

 reniform and subentire to ovate-lanceolate and doubly incised : fertile division 

 2 to 4-pinnate. — Throughout North America. Exceedingly variable, with 

 many described varieties and synonyms. 



* * Base of stalk which encloses the bud open along one side : sterile division 



membranaceous, the cells of the epidermis flexuous. 



5. B. Virginianum, Swartz. Plant sparsely hairy, 8 to 24 inches high : 

 sterile divisions sessile near the middle of the plant, broadly triangular, ternate ; 

 primary pinnae short-stalked, 1 to 3 times pinnatifid ; secondary pinnae ovate- 

 lanceolate ; ultimate segments toothed at the ends : fertile division 2 to 4-pin- 

 nate. — From Washington to Colorado (Brandegee) and Texas, and eastward 

 across the continent. 



Order 96. FILICES. (True Ferns.) 



Leafy plants ; the leaves (fronds) often much branched, circinate in 

 vernation, rising from a rootstock : spores of one kind, borne on the 

 under surface or margins of the leaves in sporangia (with an elastic 

 ring), which are developed from a single epidermal cell (hence modified 

 trichomes) : prothallus above ground, green. — The sporangia are usu- 



