400 MR. G. BENTHAM ON COMPOSITE. 
2. Eupatoriacee. 
Eupatoriacese may be regarded as one large and natural essen- 
tially American group or genus in an extended sense of the term ; 
for, multifarious and distinct as it is, some of the last mentioned 
small groups or monotypic genera of Vernoniacez rank as high in 
the latter respect. Eupatoriacee must, therefore, either not be 
so ancient as some other groups of Composite, or some other 
reason must have interfered with their early dispersion; for 
although abundant and evidently early established over the whole 
of temperate and tropical America, from California to Chili and 
Buenos Ayres, as evidenced by the distinct local generic groups 
they have formed in North America, in the Mexican region, 
in the tropical Andes, in Brazil, and in Chili, they are either wholly 
absent or have not, with the single possible exception to be pre- 
sently mentioned, produced any distinct species in tropical or 
transtropical Africa, Asia, or Australia. They are indeed entirely 
absent from the Australian flora, and would be also wanting in 
the floras of tropical and southern Africa and tropical Asia, but 
for three essentially American genera, Adenostemma, Ageratum, 
and Mikania, which have each one cosmopolitan species, and will 
be considered hereafter, and for one or two species of Eupatorium 
itself, which from Northern Asia may have penetrated within the 
tropical limits. 
This leads us to the northern and sole connexion of Eupatori- 
acese with the Old World, which may be observed in two genera: 
—1st, in the wide-spread American genus Eupatorium itself, 
whieh has in that continent above 400 species, and is represented 
in the Old World by about 8 or 10 rather variable species, all of 
one North-American type, although not exactly identical with 
any one species of that country, most of them from Eastern 
Asia, one of which extends over the whole of Europe, another 
(by some considered an extreme variety of an Asiatic one) is 
scattered over the Mediterranean region, and reappears almost in 
the same form in the Canary Islands, and another, also near the 
Asiatic ones, has been found on the Zambesi in south tropical 
Africa. There is, indeed, such a general family likeness between 
these Old-World forms and some of their E. North-American 
congeners, that they may well be imagined to have sprung from 
some parent race that may have passed over from America, and 
in the various vicissitudes of their career through the lapse of 
ages, spreading gradually over a vast extent of territory, disappear- 
