FILICES. 



333 



SuKouDKu r. POLYrODIACE/K 



Sporangia globular, or slightly llaltcned laterally, collected in patches, lines or 

 (lots of various shapes, stalked, and provided with a vertical incomplete many- 

 jointed ring, which straightens at maturity and discharges the very minute 

 spores. 



Tribe I. POLYPODIE/E. Sori lonn.l or ol.lons, placed on the veins or at the ends of the 

 veuis, destitute ol nidusuun Stalk articulated to a sljrrhtiy prominent knob of tlie usually 

 elongated creepnig rootstock. Veins free or variously reticulated. 



1. Polypodium. (Character of the tribe, of which it is the only genus. ) 



Titiiu.: II. GRAMMlTipE/E. Soii more or less elongated, without indusium, placed on the 

 back of the frond or its divisions, and usually following th.; veins, or only at the tii)s of the 

 latter and near the margin of the frond. Fionils often scaly or tonientose, or covered be- 

 ni'atli witli colored powder. 



2. Gymnogramme. Sori much elongated, following the veins, and like them often branched 



or ivticulatcd. 



3. Notholcena. Sori but little elongate.l, often of very few sporangia, placed below the tips of 



the veins near the margin of the lobes of the frond. 



TliinE III PTElUDlvE. Sori close to th argin of the frond or its divisions, sometimes 



extending down the veins, covered, at least when young, by an invohure opening inward 

 and either consisting of the margin or produced from it. 



4. Cheilanthes. Sori minute, at the ends of the unconnected veins, covered by a usually inter- 



rui.ted involucre. — Small ferns, often woollv, chally or pulverul.Mit 

 r>. Pellaea. Sori near the ends of tlie veins, often cmfhu-nt. luvolu.Me membranaceous, contin- 

 uous round the innnules. Sterile and fertile fronds much alike and smooth ; the stalk 

 dark-colored. 

 G. Cryptogramme. Sori extending down the free veins. Involucre very broad at leno-th (lat- 

 tcne.l out and exposing the now confluent .sori. Sterile and fertile fron.ls unlike, smooth ■ 

 the stalk light-colored. ' 



7. Pteris. Sporangia home on a continuous vein-like marginal receptacle, which connects the 



ends ol the veins. Involucre continuous round the pinnules. Stalk light-colored 



8. Adiantum S|)()raiigia borne at the ends of the veins, on the underside of the reflexed mar- 



gin ol the trond. Midvein of the lunnules mostly eccentric or dissipated into forking 

 veinlcts. Stalk dark-colored. ^ 



Tridr ly. BLECIINE/E. Sori more or less elongated, borne on a fruiting veinlet or a 

 special rccepta(de parallel to tlie midrib, either near it or remote from it, aixfiirovided with 

 ft special usually concave or arched indusium attached to the receptacle outside the .sorus 

 and opening along the inner edge. 



9. Lomaria. Sori continuous from tin' base of the iiiiina to its apex, the icccpfacle iirarer the 



margin than the midvein. Fronds in our species once pinnate, the fertile ones with 

 contracted j)iiina3. 



10. Woodwardia. Sori interrnpted, forming a chain-like row eadi side of the midvein. 



Fronds in our species ample, compound ; the veins reticulated. 



TuiBK V. ASPLENIE/E. Sori more or less elongated, borne on veins obljcpie to the mid- 

 vein, covered by a special usually flattened indusium attached to the fertile veinlet bv one 

 edge and free on the other. 



11. Asplenium. Sori on the upper siih- of the fertile veinlet, less commonly on both sides of it. 



Veins free in our species. 



TniHE VI. ASPIDIE/E. Sori round or roundish, on the back or .sometimes at the tip of the 

 fertile veinlcts, naked or provided with a special indusium. Stalk not articulated to the 

 rootstock, the tropical genus Olcandra excepted. 



12. Phegopteria. Sori dot-like, minute, borne on the l)ack of the fruiting veinlets ; indusium 



none. 



13. Aspidium. Sori round, borne on the hack or at the apex of the veinlcts ; indusium orbicu- 



lar or else round-reniform. Jlostly large ferns. 



14. Cystopteris. Indusium convex, delicate, fixed acro.ss the back of the veinlet by a broad 



base, usually turned back by the ripening .sporangia. Delicate ferns w'ith small 

 fronds. 



15. Woodsia. Indusium ])lared benenth the sorus, and partly or wholly enclosing it, divided 



into irregular lobes or into a delicate fringe. Fronds small. 



