DISTRIBUTION OF TRIBES. 435 
I could find nothing in habit or structure to distinguish the 
American from the East-Indian genera. The species are distinct 
enough; but one of those of the Old World is more nearly aliied 
to the American one than to its co-citizens. 
4. AMBROSIEX, ten genera and about forty species, form so 
distinct and natural a subtribe that it has been repeatedly pro- 
posed to raise them to the rank of an independent tribe, suborder, 
or even of a distinct order; and regarding the characters of Xan- 
thium and Ambrosia alone, as they are usually expressed with a 
slight exaggeration, the separation would seem justified ; I have, 
I believe, myself somewhere assented to it; but after a detailed 
examination of all the surrounding genera, I have felt compelled 
to admit that the majority of synantherologists are correct in 
placing them under the Helianthoidee. They are, without 
doubt, connected with Artemisia as well as with Melampodinee, 
having much of the habit of the former and passing into the 
latter through Parthenice; but geographically, as well as structu- 
rally, the relationship to Melampodinex appears to me to be the 
closest. The Ambrosiez are strictly American, although three or 
four species, as in the case of Elephantopus, Eclipta, &c., may be 
widely dispersed also over the Old World, whereas the Artemisie 
belong to an Old-World series, and are themselves of the Old 
World, although they may have some identieal or representative 
species in the extratropical or mountain-regions of America. Del- 
pino, however, in his above-mentioned memoir, as well as in his 
private letters, insists on the close connexion of Artemisia with 
Ambrosiezx, forming his subfamily of Artemisiacee, which he 
thinks he has established on irrefutable grounds. But to me it 
appears this is only a very natural attaching of undue importance 
to a class of characters the study of which he has specially carried 
out with so much success. He proposes two distinct * families," 
Senecionide and Helianthace:, the one with the style truncate at 
the end with a terminal tuft or marginal ring of hairs destined to 
scrape or push the pollen out of the anther-tube, the other with 
the hairs descending along the outside of the style so as to sweep 
out the pollen. This is an old distinction which experience has 
prevented from being made generally available. If Delpino had 
not confined himself to the examination of so small a proportion 
of the varied style-forms, if he had gone through any considerable 
number of our Senecionidez and Helianthoides, he would soon 
have been stopped in his endeavours to class them according to his 
