TRIANDRIA. DIGYXIA. 85 



Flora Atl.intica. To the present section of this j^enus ap- 

 pertains the R. hirsuta of f^gypt, and the B. Coalora- 

 chis of the isle of Tanna in the I'acific. Tlie R. monan- 

 {Jra of Spain, appears to be almost an Andropogon, from 

 the diagnosis. 



The genus RotbolUa, 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 

 Xorthern 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. L, 



Masculine calix 2-valve(l, S-flowered. Corolla 

 2-valved, membranaceous, imperforate at the 

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

 terior valve indurated, resemblinj^ an involii- 

 criim of one leaf, with 2 small jDeiforated sinu- 

 ses at its base. Corolla valves numerous, very 

 thin and membranaceous. Styles 2, exserted. 

 Seed larsje, ovate, arillate. 



Nearly allied to many species of the preceding- genus. 

 Flowers monoicoiis, disposed in spikes, which are simple 

 or r.ggregated, upper ones masculine, brought Together 

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

 rior valve indurated, firml}' 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 wiiich are 

 plumose and exserted; vslves of the corolla invohuo-, mem- 

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

 rudiments of flowers which are constantly aboi live for 

 want of space. Seed large, roundly ovate, ar.lla'LC, and 

 somewhat gibbous. Perisperm large, corneo!;s and fa- 

 rinaceous; corculum laterally attached, naked. Necta- 

 rium of the male flowers 2-leaved, truncate and emargi- 

 nate. 



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

 in the vast prairies of die western states Z. Collins, 

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

 Schuylkill, 25 miles above Philadelphia 2. inuiiostachtjon. 



A North American genus. 



117. JEGILOPS. L. 



Calix lateral, 2-valved, mo^itly S-flowered, 

 1 



