characters of tribes and genera. 319 



6. Rhizophordm Group. 



Fronds pinnate or bipinnaie, the apex often long, attenuated 



[caudate), flagelUform, and viviparous ; segments small, 



generally nnisorus, 



A. viride, Huds. (v v.) ; A. fontanum, Bernh. (v v.) ; A. 



flabelliformo, Cav. (v v.) ; A. obtusilobium, Ilook. (v v.) ; 



A. cicutai-ium, Sw. (v v.) ; A. myriophyllum, Presl (v v.) ; 



A. divaricatum, Kunzc (v v.) ; A. rhizophyllum, Linn, (v v.) ; 



A. cirrliatum, lilrh. (v v.) ; A. rachirhizon, Sadd. (v v.) ; A. 



pinnatifidum, NtUt. (v v.). 



7. Flaccidum Group {Darca, Willd.). 

 Fronds pinnate, liipinnatc, or decompound, often varying in tJie 

 same ■plant : segments liftdly laclniatcd, hearhig uni- 

 lateral sori which are often very short, some of tJie species 

 producing numerous viviparous hulhils on the upper 

 surface. 



A. bracliyptcron, Kunzc (v v.) ; A. prolongatuin, Hook. 

 (v V.) ; A. rutaafbliuiu, Presl (v v.) ; A. lineatum, 8iv. (v v.) ; 

 A. Belangeri, Kunze (v v.) ; A. flaocidum, Forst. (v v.) ; 

 AT^ulbiferum, Forst. (v v.) ; A. Pabianum, Homhr. (v v.) ; 

 A. appendiculatum, Labill(vY.) ; A. Ricbardi, lloah. (vv.) ; 

 A. Hookeriannm, Golenso (v v.) ; A dimorphum, Kunze 

 (v V.) ; A. viviparuin, Presl. (v v.). 



Gus. — Somo of tbo species of this group are liable to 

 extreme variation in the more or less divided state of the 

 fronds. A. lineatum of Swartz for instance, is described aa 

 having entire pinnre, but cultivated plants have shown me 

 that it varies considerably, from entire to mnltifid, passing 

 into tho several daroid states represented by the dilferent 

 forms oi A. flaccidum, several of which have been described 

 as distinct species, such as A. inequale, Kunze, and A. hiji- 



