Origin and Development of the Composites. 219 
The transition from the Melampodiinae to the Milleriinae is 
effected according to the same author by the Milleriinean genera 
Riencourtia , Desmauthodium and Clibadiutn. As the last genus has 
since been shown by Blake (VII, 2) to belong to the Melampodiinae 
the affinity is apparently closer than is suggested by the arrange¬ 
ment in Fig. 7, i.e. the Milleriinae have been derived directly from 
the Melampodiinae, not from the Coreopsidinae on the same phyletic 
line. 
M elamp odium by its floral characters and distribution is indica¬ 
ted as the primitive genus of the Melampodiinae. A comparative 
examination of thegenera of the Coreopsidinae and Verbesininae shows 
that the differences between Melampodium and these genera are 
slight. Only the first seveti genera of the Verbesininae agree with 
Melampodium in having the outer achenes enclosed by the periclinal 
bracts. Of these seven only Siegesbeckia and Enhydra have some 
of the disc florets sterile, thus approaching the completely sterile 
condition of the disc florets in Melampodium. The involucre in 
Enhydra is rather special, consisting of two outer and two inner 
bracts, but that of Siegesbeckia is biseriate as in Melampodium ; the 
former genus has often five outer or calycine members and the 
latter has four or five. Other affinities between these two genera 
can be traced. The type XIII style of Melampodium can be regarded 
as a closed type VII style and this type occurs in Siegesbeckia, 
where the branches are already short. In both genera the stamens 
are type 3, the ray-florets are uniseriate, the pappus and other 
achenial hairs are absent, the receptacular paleae sometimes encircle 
the disc florets, the corolla colour is yellow, the cauline leaves are 
opposite and sometimes dentate. Siegesbeckia plants are annuals 
and so are some species of Melampodium. Both genera occur in 
the Mexican and Andine regions and extend to the Old World. 
The areas of the two genera are very similar but that of the older 
one, Siegesbeckia, is larger, since Melampodium extends in the Old 
World only into the tropical Asiatic region, while the weedy 5. 
orientalis extends into all the Old World regions. The Melampodiinae 
are, therefore, derived, not from the Coreopsidinae as suggested 
in Pig. 7, but from the Verbesininae via Siegesbeckia and 
Melampodium. 
The date of the origin of the Heliantheae is shown to be early 
by the common occurrence in Europe of the American genus Bidens 
in the upper Pliocene That it is probably much earlier than this 
epoch is indicated by the Coreopsidean achene of Carpolithus 
