468 Small.- — Pollen-presentation Mechanism in the Compositae. 
under types V and XIII may be omitted, as these types of styles occur 
wherever there is the necessary form of floret, as does also type I. The 
Eupatorieae and Vernonieae have simple styles. It will be seen at a glance 
that type IV is the form of most common occurrence, and this type is 
undoubtedly the fundamental type of style for the Compositae. The majority 
of the Astereae show styles with appendages more or less complex, and 
with this is to be correlated the great preponderance of simple stamens in 
this tribe. The Heliantheae show a very similar stage of development, but 
the Helenieae have a distinctly larger proportion of genera of the simple 
type IV. 
In the Anthemideae the great majority of genera have this type of 
style. The Inuleae are again anomalous in having a peculiar style, type XII, 
which is almost, if not quite, as simple as type IV, and is to be correlated 
with the preponderance of the higher types of stamens in this tribe. The 
Senecioneae, while showing a considerable range of structure in the style, 
have a large proportion of type IV. Indeed, Bentham describes type IV as 
the characteristic style of the Senecioneae. The Calenduleae have quite 
a special type of style, type VI. The Cichorieae, without exception, have 
the style of type I, which is the type for the ray florets in many other 
tribes. As with the stamens, the Arctotideae show a considerable percentage 
of simple styles with some of the higher types, forming a transition to the 
Mutiseae, and the latter tribe forms an ideal intermediate stage between 
the Arctotideae and the Cynareae, which have the highest form of style, 
types X and XI. 
Neglecting columns V and XIII for the above-mentioned reasons, and 
taking type IV as a base, we find that lines of development are to be found 
almost diagrammatically similar to those in Table I. As before, there are 
two short lines, one to the Anthemideae and the other to the Cichorieae; 
two main lines, the first leading to the Eupatorieae and giving off branches 
to the Helenieae, Heliantheae, Astereae, and Vernonieae, the other leading 
to the Cynareae and giving off branches to the Arctotideae and Mutiseae; 
and a fifth leading to the Inuleae. The only difference is that a sixth line 
leads to the Calenduleae, the style of which cannot be considered a transition 
stage to that of type IX. 
Thus from these tables alone we get two phylogenetic diagrams almost 
identical. This is only to be expected if the pollen-presentation mechanism 
has undergone progressive or retrogressive development, and economy of 
pollen seems to be the simplest explanation of this progressive elaboration 
of those parts which deal with the problem of delivering to each insect 
visitor a sufficient, but also a minimum, amount of pollen . 1 
1 To those who have watched the miserly way in which the pollen-presentation mechanism of 
Centaurea supplies pollen to the bees the idea of economy is sure to have suggested itself, but, of 
course, there is in this case the additional mechanism of sensitive stamens. 
