Sub-Orders, Tribes and Genera. 6i 



SYSTEMATIC ARRANGEMENT OF SUB-ORDERS, 

 TRIBES AND GENERA. 



ORDER FILICES. 



Vascular Cryptogamia with fronds usually raised on a stipe, 

 usually from a prostrate, ascending or erect rhizoma, circinate in 

 vernation. Sporangia modified trichomes of the leaves, reticu- 

 lated, one-celled, encircled by a more or less complete, jointed 

 elastic ring, collected in clusters of various forms on the under 

 surface of the frond, with or without an indusium or covering ; or 

 panicled or spiked and naked ; or borne on receptacles of various 

 kinds. Spores of various forms, minute. Prothallium above 

 ground, green, monoecious. 



SUB-ORDER I.-POLYPODIACEiE. 



Sporangia pedicelled, surrounded more or less completely by 

 a jointed, vertical and elastic ring, bursting transversely. Sori 

 dorsal or marginal, borne on a leafy frond,with or without indusia. 



Tribe I. ACROSTICHE^E. Sporangia spread in a stratum 

 over the under surface, or rarely over both surfaces of the frond. 

 Indusia wanting. 



I. Acrostichum. L. Sori covering the entire surface of the 

 upper pinnce. 



Tribe II. POLYPODIES. Sori dorsal, borne at or near 

 the ends of the veinlets, without indusia. 



II. Polypodium, L. Possessing characters of the tribe, 



Tribe III. GRAMMITIDE.1E. Sori dorsal, variously arising 

 from the veins, usually linear. Indusia absent. 



III. Gymnogramme, Desv. Sori oblong or linear, following 

 the course of the veinlets. 



IV. Notholaena, R. Br. Sori on the veins or near their ex- 

 tremities, roundish or oblong, soon confluent into a narrow 

 marginal band. 



Tribe IV. VITTARIE.*;. Sporangia borne in a continuous 

 marginal or intra-marginal turrow. 



V. Vittaria, Sm. Fronds simple, linear, grass-like. 



