74 OUR NATIVE FERNS AND THEIR ALLIES. 



often trilobed ; sporophyll long-stalked, much overtopping the 

 leaf, the panicle ample, 5' — 8' long. California to British 

 Columbia. 



§ 2. OSMUNDOPTERIS Milde. Bud pilose, enclosed in a 

 smooth upright cavity at one side of the lower part of the stalk. 

 18 15. B. Virginianum (L.) Swz. (RaTTLESNAKE-FERN.) 

 Plant from a few inches to two feet high ; sterile segment ses- 

 sile above the middle of the stalk, broadly triangular, thinly 

 herbaceous, ternate; the short-stalked primary divisions once 

 to twice pinnate, then once or twice pinnatifid ; lobes oblong, 

 cut-toothed toward the apex ; fertile segment long-stalked, bi — 

 tripinnate. Bud pilose, enclosed in a smooth upright cavity at 

 one side of the lower part of the stalk ; fertile segment recurved 

 its whole length, the longer sterile segment reclined upon it 

 Reduced forms are B. gracile Pursh. (Botrypus Virginicus 

 Michx., Osmunda Virginiana L.) New Brunswick to Florida, 

 and westward to Arizona and the Pacific Coast. 



Family 2. HYMENOPHYLLACEyE Endl. 



Plant body consisting of a creeping stem bearing scattered 

 leaves of a filmy consistency, usually translucent. Sporangia 

 provided with a ring, sessile on a thread-like receptacle which 

 is surrounded at base by a cup-shaped or two-valved involucre. 

 The family contains several genera, mostly of tropical regions, 

 only one of which is represented in our flora. 



I. TRICHOMANES Sm. Filmy-fern. 

 Sori marginal, terminating a vein, more or less sunken in 

 the frond. Sporangia sessile on the lower part of a cylindrical, 

 filiform, often elongated receptacle. Indusia tubular or funnel- 

 shaped, entire or two-lipped at the mouth. Fronds delicate, 

 pellucid. Name from Gr. rpixo/iavei, the name of some fern, 

 from rpix, hair, and fiocivotiai, producing frenzy, alluding to 

 some supposed property. A tropical and temperate genus con- 

 taining nearly 100 species. 



§ EUTRICHOMANES. 



I. T. Petersii Gray. Stipes l" — 2" long; fronds 3" — 10" 

 long, i" — 2" broad, oblong-lanceolate or obovate, entire or vari- 



