362 THE FERTILISATION OF FLOWERS. [PART III, 
REVIEW OF COMPOSIT#. 
A review of the Composites which I have more particularly 
described shows that the. special characters of the family for the 
most part secure such abundant insect-visits that the power of 
self-fertilisation may be dispensed with ; and to a great extent it 
has been dispensed with, though in this respect all gradations are 
found between such conspicuous and abundantly-visited forms as 
Taraxacum, Cnicus arvensis, and Achillea, and those which, like 
Senecio vulgaris, are only visited exceptionally, and regularly 
fertilise themselves. 
Species in this last soutien explain how it could be of 
advantage to one offshoot of the Senecionidz with still less 
éoueeaioas flowers, viz. the Artemisiaceze, to adapt themselves 
for wind-fertilisation, and to renounce entirely the insect-visits 
whose occurrence had become so rare. Delpino has shown in a 
masterly way in his work on the Artemisiacez, the small steps by 
which this change took place. 
A comparison of species in the same genus (e.g. Senecio JSacobeea 
and S. vulgaris, Cardwus crispus and C. acanthoides, Cnicus arvensis, 
C. palustris, and C. nutans), or of closely allied genera, shows clearly 
that in the Compositz, as in other cases, the abundance of insect- — 
visitors increases with the conspicuousness of the flowers, and the 
variety of insects with the accessibility of the honey. It is only 
in a few forms with solitary, inconspicuous capitula, devoid of 
ligulate marginal florets (Gnaphalium uliginosum, Senecio vulgaris), 
that insect-visits, and consequently cross-fertilisation, are rare. 
If we compare in regard to the variety of insect-visitors, not 
isolated genera (Salix, Scabiosa, Jasione), but whole families, with 
the Composite, we find that the Umbelliferee alone rank with — 
them; indeed they in some cases surpass in this respect the most 
favoured Composites. But corresponding to the different con- 
ditions of the honey in these two orders, there is this remarkable 
distinction, that the Umbellifere: are visited and fertilised mainly — 
by those insects which are least specialised for floral nutriment, 
while most Composite are to a greater extent. or even principally, 
visited by the most specialised orders of insects. To make this 
distinction quite evident, I have arranged in the following table 
ten of the commonest forms of each order with their visitors, 
choosing plants with whose insect-visitors I was best acquainted. 
Od es a ee, 
