FERN FAMILY. 361 



6. NOTHOL^NA. Fronds once or twice pinnate, woolly, scaly or powdery be- 

 neatli ; fruit-dots at tlie ends of the veins, forming a line next the margin of 

 the divisions. 

 § 3. Spore-cases on the back along (he margin of the frond, provided with an invo- 

 lucre foi'med of its rejtexed and more or less altered margin. 



6. ADIANTUM. Fruit-dots at the ends of the veins, borne on the inner side of a 



reflexed portion of the margin. Stalk dark and polished, sometimes chaffy- 

 bristly. Pinnules always separate, distinctly stalked or almost sessile, but 

 never decurrent on the rhachis. 



7. PTKRIS. Spore-cases on a transverse veinlike receptacle within the margin, 



which connects the ends of the veins, and is covered by the reflexed thin 

 margin. Stalk light-colored (except in § Doryopteris.) Pinnules or ultimate 

 segmsiits adnate to the rliachis, often decurrent. 



8. PELL^A. Spore-cases in short lines on the upper part of the veins, confluent 



in a sub-marginal band of fructification, white within, more or less covered 

 by the reflexed and commonly thin margin. Stalk dark and polished, some- 

 times chaffy. Pinnules mostly distinct, sessile or nearly so. 



§ 4. Fruit-dots oblong or linear, on transverse reticulating veinlets, in rows near the 

 midrib and parallel to it: indusluin of the same shape as the fi"uil-dtit, opening 

 toward the midrib and attached by the outer edge to the fruitful cross-vtinlet. 



9. WOODWARDIA. Fruit-dots straight, oblong-linear, in chain-like rows, partly 



sunken in shallow cavities of the under surface of the frond. Rather large, 

 native. Veins reticulated, often very much so. 



10. DOODIA. Fruit-dots oblong, often slightly crescent-shaped, not sunken in the 



frond. Exotics; the narrow fronds pinnatifid or simply pinnate. 



§ 5, Fruit-dots oblong or linear, on one or both sides of oblique veinlets, with invohir 

 cres of like shape attached by one edge to the vtinlet and free along the other. 



11. ASPLENIUM. Fruit-dots single and placed on the upper side of the veinlets, 



rarely double and set back to back on both sides of the same veinlet. Veins 

 mostly free. 



12. SCOLO'PENDRIUM. Fruit-dots linear, elongated, double and placed face to 



face along contiguous veinlets ; each pair thus seeming to be a single one 

 vith an indusium opening along the middle. Frond simple, ribbon-shaped 

 O' tongue-shaped, with free forking veins. 



13. CAVIP rOSORUS. Fruit-dots various, mostly short; those near the midrib 



double as in the last; the outer ones angled, curved or straight, simple as in 

 Asplenium. Frond simple, tapering to a long and narrow usually rooting 

 point. Veins reticulated. 



§ 6. Fruit-dots on the back of the veins, rarely at ike ends, round or roundish, covered 

 <A least when young by a special indusium of the same general shape. Sterile 

 a%d fertile fronds alike or nearly so. 



15. ASPIDIUM. Indusium flat, round or kidney-shaped, fixed at or near the cen- 



tre, opening all round the edge. Mostly rather large Ferns, from once to thrice 

 pinnite. Veins free in the native species. 



16. CYSTOPTERIS. Indusium convex, fixed by the base partly under the fruit- 



dot, at length reflexed. Small Ferns, with delicate twice or thrice pinnate 

 fronds. Veins free. 



§ Sterile fronds broad and leafy: fertile ones with contracted and rolled up and pod- 

 like or berry-like divisions : indusium rei-y obscure, irregularly semicircular, 

 placed at the base of a short receptacle to which the spore-cases are attached. 



17. STRUTHIOPTERIS. Sterile fronds tall, with free veins, growing in a crown; 



fertile fronds coming up much later in an inner circle, pinnate, each pinna 

 rolled up from the edges into a somewhat cylindrical or necklace-like body, 

 containing the fruit. 



18. ONOCLEA. Fronds scattered on along creeping rootstock; sterile ones with 



reticulated veins; fertile ones twice pinnate, the divisions contracted, rolled 

 up and berry-like. 



§ 8. Involucres star-shaped, tvith broad and ragged or else capillary and jointed rays, 

 placed on the veins under the round fruit-dots, sometimes at first enveloping 

 the spore-cases. 



19. WOODSIA. Small Ferns, often growing in dense tufts: fronds once or twice- 



piuuate : veins forked, free. 



