1040 POLYPODIACEAE 



segments, and with broader rhomboid tips, the segments crenulatc; panicle of 

 the sporophyll diffuse. Fields and open woods: Ont.— Que.— N.J.— Pa.— Wis • 

 Alaska— B.C. — Calif. SuhmonL—Moni. 



Family 2, POLYPODIACEAE. Fern Family. 



Sporophytes consisting of a rhizome and leaves (fronds) coiled in the bud. 

 Sterile fronds leaf-like, fertile fronds (sporophylls) either leaf-like or par- 

 tially or completely non-fohaceous, bearing the sporanges on their lower sur- 

 face or at their marguis, commonly in clusters (sori). Sori naked or fur- 

 mshed with a special covering (indusium). Sporanges stalked, furnished 

 with an iiicomplete vertical ring of thickened cells (annulus), opening trans- 

 versely. Prothallia green, above ground. 



Fertile fronds. Avith contracted berry-like or necklace-like subdivisions, not foliaceous. 

 Veins of tlie sterile fronds netted. i Ovornri 



Veins of the sterile fronds free. 2 PtfrftIV 



Fertile and sterile fronds foliaceous, alike or differing- veins free 



Son on the under siirface of the fronds, each provided with a special indusiimi not 



connected with the margm of the frond. 

 Sori roundish. 



Indusia inferior or attached at base at one side of the sorus. 



Indusia mferior stellate or split mto spreading lobes. 3. Woodsia. 



indusia attached at base at one side of the sorus, at first arched over it, 

 ^ nnally thrown back or evanescent. 4 FiLix 



Indusia superior, 



Indusia peltate. 5. polysticiium. 



Indusia orbicular-reniform, adherent at the sinus. 



Mid veins and midribs united at a wide angle; fronds usually pro\'ided 

 with true hairs, consisting of a single cell or a single row of cells. 



TVT-j • J - , ., . 6. Thelypteris. 



Midveins and midrib umted at a very acute angle; fronds lacking true 



Son oblong or linear, or shaped like a horseshoe or shepherd's crook. 



feori all straight or rarely shghtly curved, smgle on the sides of the vems. 



^^^h **,^®^*: ^ P'Y*. shaped like a horseshoe or shepherd s crook, crossing the 

 . , fertile vem and more or less recurved upon it. 9. Athyrium 



won naked, or protected, at lea.st at first, by the revolute or reflexed margins or por- 

 tions of the margms of the frond. 

 Margin of the frond flat or merely revolute, not modified. 



Margin of the frond revolute; sori more or less confluent, forming a marginal 



band. ^ , ^ 16. Nothoi^vena. 



Margm of the frond flat; sori dot-like on the veins. 



Stipes jointed to the rliizome, 15 PoLYPonn^mf 



Stipes not jointed to the rliizome. 6. Thelyptekis. 



Margin of the frond reflexed over the sori. more or less modified. 



Son borne on the under side of reflexed lobes of the frond. 10. Adlixtl^i. 

 fc>ori not borne on the under side of the reflexed portions of the margin of the 



frond. 



Sori borne on a contmuous vein-like receptacle connecting the ends of the 

 yemlets. 11. Ptekis. 



Sori borne on the veins at or near their tips. 



Sori extending down the veins; edges of the fertile fronds finally open- 

 ing out flat; sterile and fertile fronds markedly dissimilar. 



c . . , , . , 12. Cryptogiluim-\. 



Son niargmal or submargmal; sterile and fertile fronds ahke or some- 

 what dissimilar. 



Sori confluent, forming a submarginal band; segments of the fronds 



glabrous or nearly so. 13. Pellaea. 



Son distmct or contiguous; segments usually pubescent, tomentose 



oT^c^Xy. 14. Cheilaxthes. 



1. ONOCLEA L. Sensitive Fern. 



Ferns, with coarse dimorph 

 ile fronds foliaceous. 



gomes. Ster- 

 like 



Sori roundish on elevated receptacles, partly covered by deUcate hood-Uke indusia 

 attached to the bases of the receptacles. 



1. O. sensibilis L. SterHe fronds 3-13.5 dm. high, deltoid-ovate, pmnat- 

 ifad; segments lanceolate^oblong, entire, undulate or smuate-pinnatifid: rachis 

 ^-mged; vems anastomosmg: fertile fronds 3-7.5 dm. hieh. bminnntn- nmnnlp« 



