494 FERN FAMILY. 



W. angustifdlia, Smith. Fronds 6'-12' long, 4'-6' broad, pinnatifid 

 almost to the winged rhachis intd 17-27 lobes, which are broadly lanceo- 

 late with copiously reticulated veins in the sterile frond, but are nar- 

 rowly linear in the fertile, with a single row of narrow meshes next 

 the midrib ; fruit dots linear, sausage-shaped, one in each mesh. N. Eng., 

 S., near the coast ; also on L. Mich., Ark., etc. 



11. BLECHNUM. (Old Greek name.) 



B. Brasiliense, Desv. Trunk 2-3 high, from the top of which arise 

 many long, oblong-lanceolate, pinnatifid fronds, curving outwards 2-3 ; 

 segments very numerous and leathery. Brazil and Peru. 



B. occidentals, Linn. Fronds arising from the surface of the ground, 

 9'-18' long, and half as broad, pinnate ; the pinnse 6-12 opposite pairs of 

 leathery texture and oblong and entire, with an auricled or heart-shaped 

 base. W. Indies. 



12. ASFLENIUM, SPLEENWORT. (Greek: refers to supposed 

 action on the spleen.) A very large genus, the size of the species 

 ranging from quite small up to very large and even tree-like. 



1. Fronds undivided, large and showy ; cult, from East Indies, etc. 



A. Nidus, Linn. BIRD'S-NEST FERN. Fronds numerous, broadly lance- 

 olate, 2-4 long, 4'-8' wide, entire, short-stalked, arranged in a crown 

 around the central upright rootstock ; fruit dots very narrow, elongated, 

 crowded, running from the stout midrib obliquely half way to the margin. 



2. Fronds small, pinnatifid below, tapering into a long, entire point; 



native. 



A. pinnatlfidum, Nutt. Very rare, near Philadelphia, and sparingly 

 W. and S., especially along the Alleghanies ; fronds 3'-6' long, "-l|' 

 wide at the base ; lobes roundish-ovate, mostly obtuse ; fruit dots small, 

 irregular. g Fronds simp i y pinnatef 



* Small ferns, 4 '-15' high. 



A. Trichdmanes, Linn. Common, forming dense tufts in crevices of 

 shady rocks ; fronds linear, 4'-8' long, with black and shining stalk and 

 rhachis, and many roundish or oblong, slightly crenated or entire pinnse, 

 about ' long and about half as broad ; fruit dots few to each pinna. 



A. ebfcneum, Ait. Frequent in rocky woods ; fronds linear-lanceolate, 

 narrower at the base, 8'-15' long, l'-2' wide ; stalk dark and polished ; 

 pinnae many, linear-oblong, often slightly curved, finely serrate, auricled 

 on one or both sides at the base ; fruit dots numerous. 



A. flabellifdlium, Cav. Cult, from Australia; lax, the rhachis often 

 prolonged and rooting at the very end ; fronds linear ; pinnse sharply 

 wedged-shaped at the base, the broad and rounded end crenated ; fruit 

 dots irregularly radiating from the base of the pinnse. 



* * Large ferns, l-3 high. 



A. angustifdlium, Michx. Rich woods, N., and S. mainly along the 

 mountains ; fronds thin, long-lanceolate ; pinnse many, 3'-4' long, linear- 

 lanceolate from a truncate or rounded base, acuminate, nearly entire ; 

 those of the fertile frond narrower; fruit dots slightly curved, very 



4. Fronds more than once pinnate. 

 * Fruit dots more than one in each smallest division of the frond. 



A. Rfcta-muraria, Linn. WALL RUE. On exposed cliffs of limestone, 

 from Vt., W. and S. ; fronds small, l'-4' long, ovate, twice or thrice pin- 



