iv.] DAISY. 29 



There is a marked difference in form between the outer 

 and inner florets of the flower-head, due to the one- 

 sided enlargement of the corolla in the former. The outer 



FIG. 18. Vertical section of a flower-head of Daisy. The outer florets wuh 

 strap-shaped corollas for.n the ray, the inner, small, tubular florets, 

 the disk. 



florets with one-sided, white corollas, taken together, 

 form the ray of the flower-head ; the smaller yellow florets, 

 with regular corollas, occupying the centre of the head, 

 form the disk, 



In describing the structure of flower-heads (capitula), 

 it is well to examine the ray and disk florets separately. 

 Neither of these appears, at first sight, to have a calyx. 

 Analogy, however, affords sufficient reason to conclude 

 that each floret has its own calyx, but it is wholly 

 adherent to the ovary. It is superior and gamosepalous. 

 In many plants related to the Daisy the Thistle for ex- 

 ample the upper, free portion (limb] of the calyx exists 

 as a crown of fine bristles surrounding the top of the 

 ovary. 



The corolla of the ray florets is (white) gamopetalous 

 and irregular ; of ths disk florets (yellow) gamopetalous 

 and regular. The stamsns in the ray florets are absent 

 or imperfect ; in the disk florets they are five in number 

 (pentandrous), and inserted upon the corolla. In con- 

 sequence of this adhesion to the corolla they are termed 

 epipetalous. 



An important character which the stamens present is 

 yet to be noted, but from the minuteness of those organs 



