P TERID OPH YTA. 19 



rocks, N. S. to N. N. Y., Wis. and Br. Col., south to Ga., Ala., the Ind. Terr, and 

 Ariz. Ascends to 670 m. in Va. July-Aug. 



17. DENNSTAEDTIA Bernh. 



Large ferns with 2-3-pinnatifid leaves, and creeping or erect rootstocks. Sori 

 small, globular, marginal or submarginal. Sporanges borne in an elevated globular 

 receptacle, enclosed in the membranous cup-shaped inferior indusium, which is 

 open at the top and on the outer side adherent to a reflexed toothlet of the leaf. 

 Sporanges pedicelled, provided with a vertical ring which bursts transversely. 

 Veins always free. [Named in honor of August Wilhelm Dennstedt, a student of 

 the Flora of Weimar.] About 30 species of wide distribution. 



I. Dennstaedtia punctilobula (Michx.) Moore. (I. F. f. 22.) Rootstock 

 creeping, not chaffy. Stipes stout, chaffless, pale green and sweet-scented ; leaves 3- 

 zodm. long, 12-20 cm. wide, ovate-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. In various situations, most abundant on open hill- 

 sides, N. B. and Ont. to Ind. and Minn, (according to Upham), south to Ala. and 

 Tenn. Ascends to 1680 m. in Va. Aug. (Dicksonia punctilobula A. Gray.) 



18. MATEUCCIA Todaro, 1866. \_Struthiopteris Willd, 1809. Not Scop. 1760.] 



Coarse ferns growing in a crown from an erect rootstock, with the sporophylls 

 closely rolled together into necklace-like segments entirely unlike the broad bi- 

 pinnatifid sterile leaves. Veins free. Three species of the northern hemisphere. 

 i. Mateuccia Struthiopteris (L.) Todaro. OSTRICH FERN. (I. F. f. 15.) 

 Rootstock stout, ascending, bearing a circle of sterile leaves with one or more 

 fertile ones within. Fertile leaves 3-5 dm. high, simply pinnate with necklace- 

 shaped pinnae which are formed of the closely revolute margins ; sori crowded and 

 confluent ; sterile leaves 6 dm.-2 m. high, 1.5-4 dm. wide, broadly lanceolate, bi- 

 pinnatifid, much the broadest above the middle and gradually tapering below, the 

 lower pinnae being gradually much reduced ; veins pinnate, free and simple ; 

 texture firm ; rootstocks stoloniferous. In moist thickets, especially along streams, 

 N. S. to N. J., west to 111. and Br. Col. Also in Europe and Asia. 



19. ONOCLEA L. 



Coarse ferns, with leaves growing separately from a wide creeping slender 

 rootstock, with the sporophylls closely rolled up into berry-like segments, and en- 

 tirely unlike the broad pinnatifid foliage leaves. Sori round, borne on the back 

 of the veins. Indusium very thin and membranous, hemispheric or hood-shaped, 

 fixed at the inferior side) of the sorus. Sporophylls unrolling at maturity, allowing 

 the spores to escape, and remaining long after the sterile leaves have been killed 

 by frost. Veins forming small areolae. [Name ancient, not originally applied to 

 these plants.] A single species. 



i. Onoclea sensibilis L. SENSITIVE FERN. (I. F. f. 14.) Rootstock rather 

 slender, rooting ; sporophylls 3-7 dm. high, persistent over winter, much contracted, 

 and with short pinnules rolled up into berry-like closed involucres forming a narrow 

 panicle; foliage leaves 3-13 dm. high, broadly triangular, deeply pinnatifid, the 

 segments lanceolate -oblong, entire, undulate, or the lower pairs sinnuate-pin- 

 natifid ; veins freely anastomosing ; lowest segments tapering both ways from the 

 middle. In moist soil, Newf. and Ont. to Minn, and south to the Gulf. Ascends 

 to 900 m. in Va. Various forms intermediate between sporophylls and foliage 

 leaves occur. Sensitive to early frosts. Aug. -Nov. 



Order 2. SALVINlALES. 



Aquatic or uliginous herbs with entire or 2-lobed, filiform, or 4-folio- 

 late leaves. Spores of two kinds and sizes (microspores and macrospores) 

 contained in sporocarps. 



Plants rooting in the mud; leaves 4-foliolate or filiform. Family i. Marsileaceae. 



Plants floating ; leaves entire, or 8-lobed. Family 2. Salviniaceae, 



