488 FERN FAMILY. 



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



sub-marf^inal band of fructification, white within, more or less covered by the re- 

 flexed and commonly thin margin. Stalk dark and polished, sometimes chaflfy. 

 Pinnules mostly distinct, sessile or nearly so. 



9. CHEILANTHES. Fruit dots minute and at the ends of the veins, distinct or nearly 



contiguous, and covered by an indusium formed of the reflexed margin of the pinnule 

 or of its lobes. Fronds mostly hairy or chaffy, low, 2-3-pinnate, the sterile and 

 fertile ones nearly alike. 



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

 midrib and parallel to it ; indusium of the same shape as the fruit dot, opening 

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



10. WOODWAllDIA. 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 retic- 

 ulated, often very much so. 



11. BLECHNUM. Fruit dots linear and nearly or wholly continuous, parallel with the 



midrib and close to it. Indusium thin and membranaceous, distinct from the edge 

 of the frond. Veins forked, usually free. Fronds pinnate (in ours). 



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

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



12. 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. 



13. SCOLOPENDRIUM. Fruit dots linear, elongated, double and placed face to face along 



contiguous veinlets ; each pair thus seeming to be a single one with an indusium 

 opening along the middle. Frond simple, ribbon-shaped or tongue-shaped, with free 

 forking veins. 



14. CAMPTOSORUS. 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. Frtiit dots on the back of the veins, rarely at the ends, round or roundish, covered 

 at least when young by a special indusium of the same general shape (except in 

 No. 15). Sterile and fertile fronds alike or nearly so. 



15. PHEGOPTERIS. Agrees with Polypodium in most respects ; but has the fruit dots 



smaller, and commonly on the free veins, not at their ends, and the stalk is not artic- 

 ulated to the rootsto<'k. Indusium 0. Fronds thin, ternate or bipinnate. 



16. ASPIDIUM. Indusium flat, round or kidney-shaped, fixed at or near the center, open- 



ing all round the edge. Mostly rather large Ferns, from once to thrice pinnate. 

 Veins free in the native species. 



17. CYSTOPTERIS. Indusium convex, fixed by the base partly under the fruit dot, at 



length reflexed. Small Ferns, with delicate twice or thrice pinnate frond. Veins 

 free. 



18. NEPHROLEPIS. Fruit dots circular, borne on the tip of the upper branch of a vein, 



and usually close to the margin of the frond. Indusium roundish or kidney-shaped. 

 Forms pinnate, with the pinnae articulated at the base, white-dotted above, the veins 

 all free. 

 § 7. Inrolucres star-shaped, with 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 pinnate ; 



veins forked, free. 

 § 8. Sterile fronds broad and leafy ; fertile ones with contracted and rolled up 

 pod-like or berry-like divisions ; indusium very obscure, irregularly semicir- 

 cular, placed at the base of a short receptacle to tvhich the spore cases are 

 attached. 



20. ONOCLEA. Fronds scattered on a long creeping rootstock or growing in a crown; 



sterile ones either with reticulated or free veins ; fertile ones pinnate or twice pin- 

 nate, the divisions contracted, rolled up and berry-like. 



