Origin and Development of the Composite. 207 
derivation of this sub-tribe from the Ligularia type of Senecio is 
confirmed by the floral morphology, by the general habit and by the 
slight or slow irritability of the stamens or its complete absence in 
that type of Senecio. 
Apart from Wemeria, which is possibly a polyphyletic genus, 
the Othonninae are clearly of recent South African origin, with 
Euryops as a probable primitive genus. Euryops is distinguished 
from Senecio only by its fused periclinal bracts and the wavy setae 
of the pappus. The Othonninae are also connected with Senecio 
through Othonna and Othonnopsis, but the differences are greater 
along that line, and although Othonna has more species than 
Euryops the area occupied by the latter genus is greater. 
Cichoriece. The derivation of the Cichorieae from the 
Senecioneae involves very few changes of any magnitude. The 
pollen-presentation mechanism is of a simple type ; the peculiar 
folding of the exine is approached in Senecio vulgaris ; the 
homogamous, non-radiate capitulum is similar to the discoid 
species of Senecio ; the predominance of yellow as a corolla colour 
and the simpler types of pappus which occur are other characters 
which show the affinity ; still others are the simple, small, almost 
flat receptacle, the uniseriate pericline with or without a slightly 
developed calyculus, and the alternate phyllotaxis of the cauline 
leaves. The occasional occurrence of leceptacular paleae is to be 
considered a reversion to a pre-Composite ancestor. The posterior 
split of the corolla and the development of laticiferous vessels are 
the two chief changes and these also are clearly of the nature of 
reversions to the Lobelioid ancestors of the Senecioneae. 
The sub-tribes are rather artificial, but we can distinguish the 
Lactuca-Sonchus group as primitive and the Scorzonera group as 
advanced. Lactuca is indicated as the primitive genus by all the 
characters of the florets and inflorescence, the seeds and seedlings, 
the chromosome numbers, and the geographical distribution. 
The time and place of origin of the tribe are both clearly 
shown ; the centre of origin is shown to be the Mediterranean region 
by the present geographical distribution; the occurrence of the 
Lactuca type and other Cichoriaceous material in the Lower 
OligoceneofAix-en-Provence is in accordance with this conclusion 
and at the same time gives the date of origin as that period or a 
little earlier. 
Calendulece. The Calenduleae are closely allied to the 
Senecioneae in the structure of the styles and stamens, in the 
