590 FiLiCES. (fekns.) 



1. p. vulgare, L. Fronds oblong in outline, green both bides (6'-10' 

 high); the divisions linear-oblong, obtuse, minutely and obscurely toothed. — • 

 Eocks; common. July. (Eu.) 



* * F7'onds twice pinnatijid, triangular , membranaceous^ annual : fruit-dots minute. 



2. P. Pliegdptcris, L. Sialk somewhat chaffy and downy ; frond nar- 

 rowly triangular in outline, longer than broad (3' - 6' long), hairy on the veins ; 

 pinna; linear-lanceolate, clos-ly ap^-oximated, the lowest pair deflexed and 

 standing fonvards; their div eions linear-oblong, obtuse, entire, each bearing 

 about 4 fruit-dots towards the base and near the margin. (P. connectile, Michx.) 

 — Damp woods; common northward. July. (Eu.) 



3. P. liexag'Ondpterum, Michx. Stalk smooth ; frond broadly trian- 

 gular, the base (7'- 12' broad) usually exceeding the length; pinnte rather distant, 

 the lower of the lanceolate obtuse divisions toothed, decurrent and forming a 

 conspicuous wing to the rhachis. — Rather open woods ; common, especially 

 soutliward. — Smoother and larger than the last. 



# * * Fronds membranaceous, ternate, the primary divisions mostly twice pinnate. 



4. P. Drydpteris, L. Stalk slender and brittle, smooth ; frond smooth 

 (pale light-green, 4' - 6' wide) ; the 3 principal divisions widely spreading ; lobes 

 oblong, obtuse, nearly entire; fruit-dots marginal, finally contiguous. — Var. 

 CALCiKEUM (P. calcareum, Smith) is more rigid, and minutely glandular-mealy 

 on the rhachis and midribs. — Rocky woods ; common northward. July. (Eu. ) 



^ 2. MARGINARIA, Bory. — Veins reticulated, forming nrostly 6-sided meshes 

 around the free veinlets which bear the fruit-dots : stalks and back of tlie thick or 

 coriaceous frond beset with firm scurfy chaffy scales. (This is probably a distinct 

 genus ; but in our species the veins are so hidden in the coriaceous frond, that 

 they can seldom be seen at all.) 



fi. P. incauum, Willd. Fronds oblong, 2' -6' long from extensively 

 creeping firm rootstocks, grayish and very scurfy underneath with thick peltate 

 scurfy scales, almost concealing the fruit-dots, which are borne on the margins 

 of the broadly linear entire lobes. — Eocks and trunks of trees, Virginia and 

 Ohio to IlUnois, and southward. 



2. STRUTHIOPTERIS, Willd. Ostrich-Fern. (Tab. 9.) 



Fruit-dots round, on the pinn« of a separate contracted and rigid frond, the 

 margins of which are rolled backward so as to form a somewhat necklace-shaped 

 body enclosing the fruit : there are 3 - 5 pinnate free veinlets from each primaiy 

 vein, each bearing a fruit-dot on its middle : the fruit-dots are so numerous and 

 crowded that they appear to cover the whole inside. — Sterile fronds large 

 (2°-3° high), very much exceeding the fertile, pinnate, the many pinnse deeply 

 pinnatifid, all growing in a close circular tuft from thick and scaly matted 

 rootstocks. Stalks stout, angular. Pinnate veins free and simple. (Name 

 compounded of a-rpovSos, an ostrich, and jrrfpif , u. fern, from the plume-like 

 arrangement of the divisions of the fertile frond.) 



1. S. Ciernianica, Willd. (S. Pennsylvanica, JF'iVM. )— Alluvial soil ; 

 not rare northward. Aug. — Fronds of this in a curious abnormal state, inter- 



