398 MR. G. BENTHAM ON COMPOSITAE. 
which has retained more permanency in the former than in the 
latter region. 
The reduced pappus is common to the New and the Old World, 
but more frequent and more regularly connected with that of Ver- 
nonia in the latter than in the former. Centratherum, with the 
sete exceedingly caducous and usually a peculiar involucre, is 
common to both regions, but much more marked in America, 
where it is limited also to one or two species passing into Oiosper- 
mum without any pappus at all, and never having any near approach 
to the ordinary pappus of Vernonia; whilst in Asia and Africa it 
is connected by various gradations with Vernonia, especially with 
the section Cyanopis, in which also the pappus is frequently deci- 
duous, and does not seem to pass gradually into the African pappus- 
less genera Ethulia and Gutenbergia. Thelatter,indeed,' especially 
Ethulia, seem to be more nearly connected with Herderia, also 
African, in which the developed pappus has a very different 
character from that of Vernonia and its modifications. 
4th. Divergences in the involucre.—These are so great within 
the genus Vernonia itself, that they are scarcely admissible as 
distinctive generic marks, except when combined with other 
characters as in the above-mentioned Centratherum and Oiosper- 
mum, or with habit and geographical isolation, as in the Cuban 
Lachnorhiza, to which also I have already referred. 
5th. Divergence in the general inflorescence.—A large group 
of American Vernoniacew diverge gradually from the typical 
Vernonie in their compound inflorescence—the flower-heads, 
either 1- or few-flowered, being closely sessile several or many 
together on a common receptacle, so as to give the whole mass 
the general appearance of a single capitulum. In Lychnophora 
and most of its allies this change is accompanied by an alteration 
in the pappus, which is paleaceous as in Stilpnopappus; but in 
Eremanthus it passes sometimes almost into that of Vernonia, 
and in Vanillosmopsis into that*of Centratherum, whilst in some 
Vernonia and Piptocarphe the few-flowered capitula, sessile in 
small clusters, further connect the true Vernonie with the Lych- 
nophoree. All these modifications are American ; the Old- World 
Vernonie and groups immediately connected with them show no 
tendency to the compound inflorescence, although it is there 
exhibited in several genera belonging to other tribes. 
The mere reduction of the number of florets to very few or to a 
single one, which induced the establishment of the Separate genus 
