FILICES. 483 



Order CXXVIL FILICES. R. Broion. The Fern Tribe. 



Fructification only of one kind on the same individual. Capsules (sporangia) 

 sessile or pedicellate, free, one-celled, mostly surrounded with a more or less 

 complete elastic ring, usually collected in clusters (sori) of various shapes, 

 which arise from veins on the under surface of the leaf or frond, and are either 

 naked or covered with a scale (involucre or indusium) : sometimes the capsules 

 are collected into distinct spikes or racemes. Seeds or sporules very minute. 

 — Trunks or rhizomas mostly creeping (in tropical countries sometimes arbo- 

 rescent), often scaly. Fronds circinate before expansion. 



Suborder I. POLYPODIACEiE. R. Br. The Polypody Tribe. 



Sori on the back of the frond, usually distinct, but sometimes confluent, naked or 

 furnished with an involucre. Capsules nearly surrounded with an articulated 

 ring, opening elastically and transversely. — Habit various. 



CONSPECTUS OP THE GENERA. 



* PoLTPODlEfi. Sori roand or elongated, withoat a partial inToIncre. 



1. PoLTPODiUM. Sori round. Fertile frond leafy. 



2. Sthuthiopteris. Fertile frond contracted ; the margin of the segments revolute, forming a general involucre : 



sori round, confluent. Pedicels of the capsules united into an elevated receptacle. 



3. ALr.osoRUS. Sori round or oblong, finally confluent and forming a broad marginal sorus, which is covered by the 



inflexed margin of the frond. Veins free. 



** Ptebidk*. Sori roundiah or elongated, transverte, marginal or costal, limple or by coniliience compound, famished with a special lateral 



involucre, the inner margin of which is free. 



4. AniANTUM. Sori roundish, reniform or linear, marginal. Involucre formed of the altered reflexed margin of the 



frond or crenules, bearing the sori on its underside. 



5. Pteris. Veinlets of the frond direct ; their apices combined by a transverse receptacle which bears the capsules 



forming a linear continuous or interrupted marginal sorus, which is bordered by the narrow involucre. 



6. Platyloma. Sori oblong, laterally confluent, forming a broad continuous marginal sorus. Involucre marginal and 



continuous. Veinlets free at their summits. 



7. Doom A. Sori oblong or linear, parallel and near the midrib. Involucre flat; the inner margin free. Veinlets 



united near their base, free at the apex. 



8. WooDWARDiA. Sori oblong or linear, parallel and near the midrib. Involucre vaulted, involute. Veins of the 



sterile frond reticulated. 



•w j^Pl.siflK.e. Sori elongated, oblique to the axis, simple or double (the two applied back to back or face to face), each furnished with a 

 special lateral linear involucre. Capsules attached to the sides of the veinlets. 



9. ScoLOPENDBicM. Sori linear, confluent in pairs ; the free margins of the involucres facing each other. Veins 



forked, free. 



10. AsPtENiuM. Sori linear, unilateral; the capsules produced on the upper side of the veinlets. Veins forked or 



pinnate ; the veinlets free. 



11. ANTiOBAMMi. Sori linear, unilateral, moctly approximate in pairs and facing each other. Veins reticulated. 



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