220 James Small. 
hyoseritifovmis from the lower Eocene of America. The wide 
distribution of some of the higher types and the more extensive 
generic differentiation in the Heliantheae than in the Astereae 
renders it probable that the lower Eocene is the latest date which 
can be regarded as probable for the origin of the tribe. Taking all 
the data into account the origin of the Heliantheae can be placed 
very soon after the origin of the family, and it is possible that the 
more primitive genera of the tribe originated in South America. 
Spilanthes shows a considerable Andine development as well as a 
centre of overlapping in South America. (See Fig. 39 and also the 
suggestion by Blake (159) that the South American section Eu- 
anrece of Viguiera is the primitive one). Although the Heliantheae 
probably arose in South America they undoubtedly attained their, 
greatest development in the Mexican and U.S. regions, and the 
origin of most of the sub-tribes is probably to be located in these last 
two regions. 
Heleniece. Throughout this investigation affinities have been 
indicated for the Helenieae with two tribes, the Heliantheae 
(Galinsoginae) and the Senecioneae. With the possibilities of 
polyphyly and convergent evolution which have been discussed, the 
close connection of the Helenieae with the Senecioneae, which was 
recognised by Bentham, and the affinities which are also shown 
with the Anthemideae and the Heliantheae, the probability is con¬ 
siderable that this tribe is an artificial one, distinguished only 
technically from the Senecioneae by the paleaceous pappus. If 
this view is correct the tribe requires reclassification on a more 
natural basis and it would serve no useful purpose to discuss the 
affinities of the sub-tribes at the present stage. 
That the origin of most or all of the genera is comparatively 
recent is indicated by the restricted distribution and the comparatively 
slight generic differentiation within the tribe. The date of the 
origin of the oldest genera, such as Pectis and PorophyIltim( Tagetinae) 
Flaveria (Flaveriinae) and jfaumea (Jaumeinae) can scarcely be earlier 
than the upper Miocene. 
