18 POLYPODIACEAE 



side auricled, the lower rounded at the base : rachis nearly naked : sori almost marginal, 

 covered by nearly orbicular, rather peltate indusia. [N. aeuta Presl.] 

 On the south bank of the Miami River, Florida. Also in tropical regions. 



28. DENNSTAEDTIA Bernh. 



Eootstocks usually horizontal. Leaves tufted : blades 2-3-pinnatifid. Sori small, globu- 

 lar marginal or nearly so. Sporanges borne in an elevated globular receptacle, enclosed in a 

 membranous cup- shaped inferior indusium, which is open at the top, and on the outer side 

 adherent to a reflexed toothlet of the leaf. Veins always free. 



1. Dennstaedtia punctildbula (Michx.) Moore. Rootstock not chaffy. Petioles 

 stout, chaffless, pale green and sweet-scented ; leaf-blades 3-10 dm. long, lanceolate, acute 

 or acuminate, frequently long-attenuate, usually 3-pinnatifid, thin and delicate ; rachis and 

 under surface minutely glandular and pubescent : sori minute, each on a recurved toothlet, 

 usually one at the upper margin of each lobe : sporanges few : indusium cup-shaped with 

 a delicate membranous irregular margin. [Dicksonia punctilobula (Michx. ) A. Gray.] 



On open hillsides, New Brunswick to Ontario and Minnesota, south to the mountains of Georgia 

 and Alabama. 



29. PILIX Adans. 



Delicate rock ferns. Leaves with slender petioles and 2-4-pinnate blades. Sori 

 roundish, each borne on the back of a vein. Indusium membranous, hood-like, attached 

 by a broad base on its inner side and partly under the sorus, early opening and somewhat 

 evanescent. Veins free. [Cystopteris Bernh.] 



Leaf-blades scarcely broader at the base, short-pointed, without bulblets. 1. F.fraqilis. 



Leaf-blades broadest at the base, long-tapering, bearing bulblets beneath. 2. F. bulbifera. 



1. Filix frdgUis (L. ) Underw. Leaves tufted ; petioles 10-20 cm. long ; blades thin, 

 oblong-lanceolate, slightly tapering below, 1-3 dm. long, 2-3-pinnatifid or pinnate ; leaf- 

 lets lanceolate-ovate, irregularly pinnatifid, with a broad central space and bluntly or 

 sharply toothed segments decurrent along the margined or winged rachis, without bulb- 

 lets : indusia narrow or acute at the free end, early withering. 



On rocks and in moist grassy woods, Newfoundland to Alaska, south to Georgia and Arizona. 

 Almost cosmopolitan. 



2. Filix bulbifera (L.) Underw. Leaves weak; petioles 10-15 cm. long, light- 

 colored ; blades elongated, lanceolate from a broad base, 3-8 dm. long, 2-3-pinnatifid or 

 pinnate ; leaflets crowded, toothed OP pinnatifid : rachis wingless, commonly bearing under- 

 neath, in the axils of the leaflets and segments, fleshy bulblets which fall away and propa- 

 gate the plant : indusia truncate on the free side, early thrown back and withering. 



On moist rocks, especially limestone, Quebec to Wisconsin, south to Tennessee and Arkansas. 



30. WOODSIA E. Br. 



Small or medium-sized ferns, growing in rocky places. Leaves often evergreen, 

 tufted : petioles often jointed above the base and finally separating : blades 1-2-pinnate or 

 pinnatifid. Sori round, borne on the backs of simply forked free veins. Indusia inferior, 

 thin and often evanescent, roundish or stellate, either small and open or early bursting at 

 the top into irregular lobes or segments. 



Indusium minute or evanescent, flat, concealed beneath the sorus, its margin cleft into hair-like seg- 

 ments. 1. W. llvensis. 

 Indusium manifest, at first enclosing the sporanges, splitting into jagged lobes. 2. W. obtusa. 



1. Woodsia Ilv6nsis (L. ) K. -Br. Leaf-blades lanceolate, 10-25 cm. long, glabrous 

 above, more or less covered with rusty chaff beneath, as are also the slender jointed peti- 

 oles ; leaflets crowded, sessile, pinnately parted, the crowded segments oblong, obscurely 

 crenate : sori borne near the margins of the segments, somewhat confluent when old : in- 

 dusium minute, concealed beneath the sorus, its margin cleft into filiform segments, which 

 are inflexed over the sporanges and inconspicuous, especially when mature. 



On exposed rocks, Labrador and Greenland to Minnesota, south to North Carolina and Kentucky. 

 Also in Europe and Asia. 



2. Woodsia obtusa (Spreng. ) Torr. Petioles not jointed, pale green, 7-15 cm. 

 long ; leaf-blades broadly lanceolate, 15-40 cm. long, minutely glandular-pubescent, nearly 

 2-pinnate ; leaflets rather remote, triangular-ovate, or oblong, pinnately parted into obtuse 

 crenate-dentate segments : veins forked, bearing the sori near the minutely toothed lobes : 

 indusia conspicuous, at first enclosing the sporanges, at length splitting into several lobes. 



On rocks, Nova Scotia to New York and British Columbia, south to middle Georgia, Texas and 

 Arizona. 



