CHARACTERS OF TRIBES AND GENERA. 319 



6. RHIZOPHORUM GROUP. 



Fronds pinnate or bipinnate, the apex often long, attenuated 

 (caudate], flagelliform, and viviparous ; segments small, 

 generally unisorus, 

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



flabelliforme, Cav. (v v.) ; A. obtusilobium, Hook, (v v.) ; 



A. cicutarium, Sw. (v v.) ; A. myriophyllum, Presl (v v.) ; 



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



A. cirrhatum, Rich, (v v.) ; A. rachirhizon, Radd. (v v.) ; A. 



pinnatifidum, Nutt. (v v.). 



7. FLACCIDUM GROUP (Darea, Willd.). 



Fronds pinnate, bipinnate, or decompound, often varying in the 

 same plant ; segments bijidly laciniated, bearing uni- 

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

 producing numerous viviparous bulbils on the upper 

 surface. 



A. brachypteron, Kunze (v v.) ; A. prolongatum, Hook. 

 (v v.) ; A. ruteefolium, Presl (v v.) ; A. lineatum, Sw. (v v.) ; 

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

 A. bulbiferum, Forst. (v v.) ; A. Fabianum, Hombr. (v v.) ; 

 A. appendiculatum, Labill (v v.) ; A. Bichardi, Hook, (v v.) ; 

 A. Hookerianum, Colenso (v v.) ; A dimorphum, Kunze 

 (v v.) ; A. viviparum, Presl. (v v.). 



OBS. Some of the 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 as 

 having entire pinnae, but cultivated plants have shown me 

 that it varies considerably, from entire to multifid, passing 

 into the several daroid states represented by the different 

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

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



