581 



FILICES. 



General Remarks on Fern's. 



Essential points of the Filical structure. Axis very dis- 

 tinct, when branched, dichotomous 



Primary roots endorhizal, secondary (?) ultimate (?) confer- 

 void. 



Leaves generally densly imbricated, scarious with no aerat- 

 ing organs, with plane equal attachments. Ramenta. 



Fronds highly foliaceous, stomata generally on the under 

 surface, during vernation spirally coiled upwards (almost in- 

 variably) veins bifurcate with clavate ends. 



Male flowers, (obviously reduced transformations from the 

 leaves, squamae etc. of authers,) reduced to their simplest 

 forms (their representatives exist in the abortive male flowers 

 of Mosses or Epiphyses), sac of the anther but little deve- 

 loped, dehiscence obscure. 



Female flowers, appearing subsequently to the application 

 of the fertilising matter to the under surface of the young 

 fronds ; consequently they have neither style or stigma. 



Calyptra none. Capsule simple, for the most part bursting 

 by means of an annulus. 



I have long since had reason to believe, that the fruc- 

 tification of the frond of a Fern, is a circumstance to be deter- 

 mined only at a very early period, and if not determined 

 at that stage of development, never appears likely to be 

 determined subsequently ; or in other words, that a frond 

 which is sterile when young, is sterile ever afterwards. My 

 attention was hence led more strongly if possible than it 

 otherwise would have been, to exmine these curious produc- 

 tions at the ealiest possible period. 



The first Fern I met with, was a species, if Adiantum, of 

 ordinary form, and I was at once struck with the similarity, 



