FRUCTIFICATION IN FERNS. 1 7 



by its broad base on the inner side of the roundish sorus and 

 partly under it. Later this is thrown back and withers away. 

 The veins are free, and the fronds have the aspect of species of 

 Dryoptcris, but are usually more delicate in texture. 



51. Onoclea. -Two quite dissimilar species have unfortu- 

 nately been united under this name, which best form two genera 

 Both have dimorphous fronds, the margin of the contracted 

 fertile frond being strongly revolute, and concealing the fruit. 

 Matteuccia has necklace-shaped pinnae, crowded confluent 

 sori, and free and simple veins. Onoclea has panicled berry- 

 shaped pinnules and copiously anastomosing veins. 



52. Woodsia (Fig. 9) has round- 

 ish sori borne on the back of the 

 veins, with the indusia attached be- 

 neath the sporangia and flat and open, 

 or early bursting at the top into ir- 

 regular laciniae or lobes. In Eu- 

 WOODSIA the indusia are flat and open _ 



r FIG. g. Jf- oodsia oHusa 



from an early stage, with their cleft Torr. Enlarged section of 



and ciliate margins concealed under and inferior indusia. 



the sori. In HYPOPELTIS the indu- 



sium is more conspicuous and encloses the sporangium at first, 



but soon bursts at the top, forming several jagged lobes. 



53. Dennstaedtia. In this genus the small globular sorus 

 is borne in an elevated, globular receptacle, and enclosed in an 

 inferior, membranous, cup-shaped indusium. The veins are 

 always free. The genus has been confused with tree-ferns. 



54. Trichomanes (Fig. 10) has 

 sessile sporangia borne on a filiform 

 receptacle at the summit of a vein. 

 The indusia are tubular or funnel- 

 shaped, with an expanded and often 

 somewhat two-lipped mouth. 



55. Lygodium. In our species 

 of climbing-fern the fructification is 

 borne on contracted, forked pinnules 



FIG. io. Trichomanes radi- 

 OCCUpying the upper portion OI the cans Swz. Enlarged section, 



frond. The ovoid sporangia are sol- 

 itary or occasionally in pairs, and are borne in the axils of the 



