Origin and Development of the Composites. 137 
That this is not merely mathematical twisting of facts to suit 
the construction can he seen from Figs. 23-24. The occurrence of 
individual capitula with 22 rays involves abnormalities in the system 
and such a case is shown between the bracts numbered 21 and 34 
in Fig. 24 (cp. Fig. 23). 
Fig. 23. Heliantlius 
annuus. Section of a 
young capitulum, 10mm. 
in diameter: cam. lucid, 
drawing of half the disk. 
(Figure and legend after 
Church.) 
Similar figures can be drawn for heads with 13, 34 or more 
rays and are widely different from the artificial figures given by 
Schwendener and Strickland. 
Disc Florets. The theoretical arrangement of the disc florets 
according to the (21+34) curve system is illustrated in Fig. 22, but, 
just as rising phyllotaxis characterises the involucre, so falling 
phyllotaxis characterises the centre of the capitulum. The spirals 
of the (21+34) system are true to nature up to a point where the 
size of the floret requires some accommodation in the arrangement. 
This is necessary because all the florets mature more less simultan- 
