Origin and Development of the Composites. 14! 
opposite in Olearia, and the normal condition with opposite lower 
leaves and alternate upper leaves in Amelins is particularly interest- 
in}* in view of the probable origin of the Eupatorieae from the 
Heterochrominae. 
The Heliantheae although advanced in all their floral characters 
show atavistic tendencies in the phyllotaxis as well as in the 
receptacle. Most of the Verbesiinae show opposite phyllotaxis 
either entirely or only in the lower leaves. About a dozen small 
genera are always alternate throughout. Alternate leaves are the 
rule with a few exceptions in the Ambrosiinae and Petrobiinae. 
Opposite leaves are the rule with a few exceptions in the Lagasceinae, 
Zinniinae, Milleriinae and Coreopsidinae. About two-thirds of the 
Melampodiinae are opposite, the rest being alternate (cp. the 
Milleriinae line in Fig. 7). The Madiinae are alternate without 
exception and the condition in the Galinsoginae is of particular 
interest. Here, as in the Heleniieae, about half of the genera show 
one type and the other half the other type. 
The detailed distribution in the Helenieae is also of interest; 
the two types occur in almost equal proportions in the Tagetinae 
and Baeriinae; opposite leaves are the rule with one exception in 
the Flaveriinae and alternate leaves the rule without exception in 
the Heleniinae, cp. Fig. 7. 
C. Phylogenetic Significance of Phyllotaxis. 
The study of the detailed phyllotaxis of the capitulum yields 
several important phyletic data ; the calyculus is proved to be more 
akin to cauline leaves than to the periclinal bracts; the distinction 
drawn between these two parts of the involucre in Chap. VI. is 
upheld ; the number and position of the ray florets is proved to be 
primarily dependent on the bracts of the pericline; the uniseriate 
type of ray is seen to be the primitive condition in radiate capitula, 
but the balance of the evidence is still in favour of the discoid 
capitulum being primitive for the family. 
The analysis of the phyllotaxis of the leaves in so far as 
they are opposite or alternate supplies phyletic evidence which, 
although of no great value, is of considerable interest in that it 
follows in some detail the phyletic lines already elucidated. 
The most interesting points are noted in Sect. B so that it is 
only necessary to direct special attention to the phyllotaxis of the 
Senecioninae, Liabinae and Vernonieae ; the Nassauviinae and the 
rest of the Mutisieae ; Buphthalminae and Cynareae ; the Heterochro¬ 
minae and Eupatorieae ; the Galinsoginae and Tagetinae ; and the 
marked atavistic tendency in the Heliantheae which is in accordance 
with the other atavistic tendencies in that tribe. 
