4» ME. G. BENTHAM ON aBAMINEJi. 



hardened and frequently more or less united at the base, the 

 inner ones often broad and scale-like. In some specimens, how- 

 ever, of O. cdlyculatus, Oav., and its allies the hardening appears 

 so slight as to bring the genus into very close connexion with 

 I'ennisetum. 



13. Pennisetum, Pers., the principal genus of the group, would 

 now contain about forty species, chiefly African, amongst which 

 two or three extend to the Mediterranean region, tropical or central 

 Asia, or tropical America, and a very few may be endemic in Asia, 

 Australia, or America. It has been at various times proposed to 

 separate several genera from it, and two or three of these have been 

 pretty generally adopted ; but they pass so gradually one into the 

 other, and their chief characters, derived from the hairiness or 

 numbers of the involucral bristles, are so little in accord with any 

 other characters or habit, that the several following groups can 

 scarcely be considered even as definite sections. Pennisetwm 

 itself has been restricted to those species in which the bristles are 

 numerous and some or all of them more or less hairy ; whilst those 

 in which the whole of the bristles are perfectly glabrous form the 

 genus Qymnotrix, Beauv. But however easy this distinction may 

 appear at first sight, it is neither natural nor always definite. In 

 a few African species proposed by Figari and De Notaris as their 

 genus EriocJicBte, the whole of the setse are densely woolly-plumose; 

 in some of the commoner species numerous outer setse of each 

 involucre are glabrous, and as many or more or fewer of the inner 

 ones are hairy. In F. flaccidum, Munro, from East India, and 

 P. BentJiamianum, Steud., from tropical Africa, amongst very 

 numerous glabrous ones there are generally only two or three 

 hairy ones, or sometimes none at all, thus forming a gradual con- 

 nexion with the true species of Qymnotrix, where the setsB are 

 always quite glabrous ; and there is nothing else whatever to 

 distinguish the two series even as marked sections. F. lanatum, 

 Klotzsch, is a remarkable Himalayan species, in which the 

 involucral bristles are few, sometimes reduced to a single long 

 rigid branched one, either plumose or glabrous, showing well the 

 true nature of the involucre of the genus. Penicillaria, Willd., 

 often still retained as a genus, was founded upon a plant frequently 

 cultivated in the Indo-African regions, which may at first sight 

 appear to be abundantly distinct. The long dense cylindrical 

 spilve or spike-like panicle is often above a foot long and an inch 

 m. diameter, although in other cultivated specimens not above 



