8O OUR NATIVE FERNS AND THEIR ALLIES. 



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

 a longitudinal slit. 



XXX. Osmunda L. Fertile pinnae or fronds much con- 

 tracted, bearing the large and abundant sporangia on the mar- 

 gins of the narrow segments. 



ARTIFICIAL SYNOPSIS OF GENERA. 



Sporangia collected in sori and borne on the back or margin of a 



j leafy frond B 



1 Sporangia in spikes or panicles not on the leafy portion of the 



[ frond U 



( Sori covered with indusia O 



( Sori naked P 



{Fertile frond closely rolled together, entirely unlike the sterile, its 

 segments berry-like or necklace-like . .XXIII. ONOCLEA, p. 119 

 Sori marginal, covered with a reflexed portion of the frond . D 

 I Sori marginal or terminal, borne on an elongate receptacle, 



XXVI. TRICHOMANES, p. 122 

 I Sori dorsal or marginal, provided with special indusia ... H 



{Terrestrial, growing mostly in rocky places E 

 Aquatic, sterile fronds floating on the water, 

 XII. CERATOPTERIS, p. 101 

 f Sporangia at the ends of the veins, borne on a reflexed portion of the 



margin of the frond VII. ADIANTUM, p. 89 



E I Sporangia borne on a continuous, marginal, vein-like receptacle con- 

 necting the apices of the veins VIII. PTERIS, p. 90 



Sporangia at or near the ends of unconnected veins, borne on the 



I under surface of the frond J? 



i Fronds conspicuously dimorphous ; stipes light-colored, 



X. CRYPTOGRAMMA, p. 97 



' Fronds nearly uniform ; stipes usually dark G 



f Sori on the upper part of the veins, mostly forming a continuous mar- 

 ginal band ; indusium membranous, continuous round the segment, 

 Q. XI. PELL^EA, p. 97 



1 Sori minute, at the ends of the veins ; indusium interrupted, or if con- 

 tinuous, the ultimate segments usually small and bead-like ; fronds 

 <- mostly chaffy, woolly, or farinose, . . IX. CHEILANTHES, p. 91 

 ( Sori roundish ; indusia not more than twice as long as broad . I 



I Sori linear or oblong ; indusia more than twice as long as broad L 



; Indusium superior, attached by the centre or sinus J 

 Indusium convex, fixed by a broad base partly under the sorus, 

 XXII. CYSTOPTERIS, p. 118 

 I Indusium inferior K 



