The Pollen-presentation Mechanism in the 
Compositae. 
BY 
JAMES SMALL, B.Sc. (Lond.), Ph.C., 
demonstrator in Botany , Armstrong College, Durham University. 
With seven Figures and two Tables in the Text. 
Introduction. 
W HEN it is remembered that this order includes over 13,000 species, 
the very voluminous literature does not come as a surprise, but in 
spite of the numerous contributions to our knowledge of- the Compositae, 
very few attempts have been made towards the elucidation of the evolution 
of even the main divisions of the order. Cassini ( 3 ), in 1826, made one of 
the first attempts to express the affinities of the tribe. He did so by placing 
the nineteen tribes, into which he divided the order, in an ellipse with the 
Vernoniees and Lactucees at one end and the Helianthes at the other, with 
twelve lines crossing the enclosed space to indicate the presence of some 
common characteristic ih tribes which he considered to be otherwise 
unrelated. In 1871 Delpino ( 5 ) gave a phylogenetic table for the Artemi- 
siaceae showing the Compositae derived from the Campanulaceae through 
the Lobeliaceae and the Artemisiaceae derived from the Senecionidae, but 
since the Senecionidae, to which reference is made here, included many of 
the genera now in the Heliantheae, Helenieae, and Anthemideae, the value 
of this speculation, for it was little more, is seen to be negligible. 
Bentham ( 1 ), in 1873, followed Cassini in his method of expressing the 
inter-relationships of the tribes with very little change, except in the reduc¬ 
tion of the number of divisions to thirteen and the placing of the Senecionideae 
between the Anthemideae and Calendulaceae instead of next the Astereae, 
as Cassini had it. In considering the affinities, Cassini does not seem to 
have thought of one tribe or its ancestors having given rise to any other 
tribe, as is shown by the form of his diagram and the numerous cross¬ 
connexions introduced, but of course he thought in pre-Darwinian terms. 
Bentham took geographical distribution as his chief guide to the evolution 
of the different groups, and considered that the order could be detected at 
its earliest recognizable stage in Africa, Western America, and possibly 
[Annals of Botany, Vol. XXIX. No. CXV. July, 1915.] 
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