CHAEACTEES OP TEIEES AND GENEEA. 339 



196.— Gleichenia, Sm. (1793). 



HooJc. S'l). Fil. ; Mertensia, WillJ. ; Vicranopteris, Bernh. ; 

 Sticherus and Cahjmella, Presl. 



Vernation sarmentose. Fronds long- stipate, 1 to 6 or 

 more feet high, once or many times dicbotomously 

 branched, ultimate divisions (pinnaj) linear lanceolate, 

 lacinfe plain or recurved and saccate, smooth, glaucous, or 

 more or less pubescent or squamose. Veins simply or 

 pinnately forked, venules free, the lower exterior one fer- 

 tile, sporang-iferous receptacle, terminal, lateral, or nearly 

 axillary superficial. Sporangia 3 to 8, forming punctiform 

 naked sori. 



Type. Polijpodlum dicliotomum, Thuiih. 

 Illust. Hook, and Bauer, t. 39 and 41 A and B ; Moore 

 Ind. Ml., p. 87, B ; J. Sm. Ferns, Brit, and For., f 136 ; 

 Hook. Syn. Fil., t. 1, fig. 3. 

 Obs. — The species of this genus present two very dis- 

 tinct aspects, which form two groups. In the first the 

 lacinse are plain, and often 1 inch or more in length, con- 

 stituting- the genus Mertensia of Willdenow ; in the second 

 the lacinffi are very small and revolute ; these are by some 

 termed true Gleichenia, Isut as the habit of growth of the 

 two groujos is the same, and there is not sufficient difference 

 in the character of the sori to warrant their separation as 

 genera, I therefore arrange the species as follows : — 



Gleichenia vera. {Gahjmella, Pr.). 

 Lobes of the pinnce small, sub-rotund, generally revolute. 



Sporangia terminal. 

 Sp. G. microphylla, B. Br. (v v.) ; G. dicarpa, J?. Br. 

 (v V.) ; G, semivestita, Labill. (v v.) ; G. hecistophylla, A. 



