TRIANDRIA. DIGTNIA. 85 



Flora Atlantica. To the present section of this t^enus ap- 

 pertains the R. hivsuta of ^'g"ypt, and the R. Coaloru' 

 chis of the isle of Tanna in the J'acific. The R. monayu 

 lira of Spain, appears to be almost an Andropogon, from 

 the diagnosis. 



The genus Rotbolliuy though not numerous in species, 

 appears to have been dispersed upon every known sea^ 

 coast; they are found upon all the coasts of Europe, of 

 Northern Africa, of America, of India, and of Australia, 

 as well as upon the remotest shores of the latest disco- 

 vered islands in the Pacific 



116. TRIPSACUM. X. 



Masculine calix S-valved, 2-flowered. Corolla 

 2-valved, membranaceous, imperforate- at the 

 base. Female calix 1 -flowered, 2-valved, ex- 

 terior valve indurated, resembling an involu- 

 crum of one leaf, with 2 small pci forated sinu- 

 ses at its base. Corolla valves numerous, very 

 thin and membranaceous. Stijles 2, exserted. 

 Seed large, ovate, arillate. 



Nearly allied to many species of the preceding" genus. 

 Flowers monoicous, disposed in spikes, which are simple 

 or aggregated, upper ones masculine, brought together 

 by pairs, each 2-flowered; female calix 2-valved, the exte- 

 rior valve indurated, firmly closing the scrobiculum, but 

 perforated by 2 small sinuses at its base, and an emargi- 

 nation, or bifid apex for the egress of the styles which are 

 plumose and exserted; valves of ti)e corolla involute, mem- 

 branaceous, about 6, extremely thin, 4 of them probably 

 rudiments of flowers which are constantly abortive for 

 want of space. Seed large, roundly ovate, arillate, and 

 somewhat gibbous. Perisperm large, corneous and fa» 

 rinaceous: corculum laterally attached, naked Necta- 

 rium of the male flowers 2.ieaved, truncate and emargi- 

 nate. 



Species. 1. T. dactyloides. On the sea-coast, and also 

 in the vast prairies of the western states. Z. Colhns, 

 Esq. informs me of its existence near the banks of the 

 Schuylkill, 25 miles above Philadelphia 2. monostaehymi. 



A North American genus. 



il7. ^GILOPS. L, 



Calix lateral, 2-valved, mostly 3-flowered, 

 1 



