456 MR. G. BENTHAM ON COMPOSITE. 
in species, has, owing to the overgrown proportions of one vast. 
genus, by far the greatest average number of species to a genus: 
nearly 1400 species are comprised in about 40 genera; but of these 
species, two thirds belong to Senecio itself, reducing the average of 
the remainder to more ordinary proportions. The tribe is divi- 
sible, according to structure, into four somewhat artificial sub- 
tribes, which, although generally confirmed by geographical dis- 
tribution, yet in this respect show some embarrassing exceptions. 
The principle subtribe, Euseneciones, is truly cosmopolitan ; 
Liabee are American, with one tropical-African exception ; 
Tussilaginee belong to the temperate northern regions, with one 
South-African exception; Othonnes to South Africa, with the 
exception of one widely spread high mountain genus. As a 
whole, the tribe is distinguished, amongst those which have tail- 
less anthers and a setose pappus, from Vernoniacesz and Eupa- 
toriacew by their yellow disk-florets and frequently heteroga- 
mous capitula, and from Asteroideew by their involucres, habit, 
and generally, though not always, by their styles. 
Senecio itself is not only the largest genus among Composite, 
but one of the largest, if not the largest, among Phenogamous 
plants, and certainly the most widely spread; truly cosmopolitan 
and ubiquitous, abounding in local species in almost every region 
of the globe, in the Old and the New World, from the equator to 
the arctic regions and the extreme south, on Alpine summits, in 
stony wastes or sandy deserts, in swamps, on sea-coasts, on the 
borders of streams, everywhere are Senecios to be met with ; and 
yet individually the species have not wide areas. No species 
is common to the New and the Old World, except in the far 
north; no one has, I believe its range interrupted by any consi- 
derable interval ; and notwithstanding the facilities for transport 
afforded by the proportions of the pappus and the achenes, few 
have a very wide area, or, as weeds of cultivation, establish them- 
selves in a new country with that readiness so marked in the 
Conyzoid Erigerons, for instance. It is, moreover, not easy to give 
any definite centre for the genus. It is less abundant, however, 
in the tropics, and most varied in temperate and cool or moun- 
tain-regions; so that some centre may be vaguely traced in the 
mountain regions and high latitudes of the northern hemisphere 
down the Andes from California to Chile, in Antarctic America, 
Southern Australia, and especially in South Africa. It is not 
easy, either, to divide it into sections or series by any combi- 
