64 Our Native Ferns. 



Tribe IX. DICKSONIEiE. Sori roundish or transversely 

 elongated, borne at the ends of the veins or on marginal cross- 

 veinlets, with an indusium attached at the base or base and sides 

 and opening toward the margin of the segment. 



XXIV. Dicksonia, L'Her. Sori marginal, small, the indusium 

 cup-shaped, somewhat two-valved, the under portion confluent 

 with a lobule of the frond. 



SUB-ORDER II. -HYMENOPHYLLACEyE. 



Sporangia borne on an elongated, often filiform, receptacle, 

 surrounded by a complete transverse ring, opening vertically. 

 Sori terminal or marginal from the apex of a vein. Indusium in- 

 ferior, usually of the same texture as the fronds. Fronds deli- 

 cately membranous and pellucid. 



XXV. Trichomanes, Sm. Indusia tubular, cup-shaped, or 

 funnel-shaped, sometimes two-lipped. 



SUB-ORDER III.-SCHIZ^ACEyE. 



Sporangia ovate, sessile, arranged in spikes or panicles, having 

 a complete, transverse, articulated ring at the apex, and opening 

 by a longitudinal slit. 



^Sterns scandent. 



XXVI. Lygodium, Swz. Sporangia borne in a double row 

 on narrow fertile segments, each on a separate veinlet and pro- 



. vided with a special indusium. 



** Stems not scandent. 



XXVII. Aneimia, Swz. Sporangia naked, attached by their 

 bases to the narrow divisions of the panicled fertile segments of 

 the frond. 



XXVIII. Schizaea, Sm. Sporangia naked, fixed in a double 

 row to the midrib of the narrow fertile segments. Sterile fronds 

 simple or dichotomously forked. 



SUB-ORDER IV.-OSMUNDACEjE. 



Sporangia naked, globose, mostly pedicelled, with no ring or 

 mere traces of one around the apex, opening into two halves by 

 a longitudinal slit. 



XXIX. Osmunda, L. Fertile pinnae or fronds much con- 

 tracted, bearing the large and abundant sporangia on t'le margins 

 of the narrow segments. 



