PRACTICAL WORK. NO. XII. 221 



c. ray florets ; 



d. disc florets. 



[The " flower" is in reality an inflorescence consisting 

 of numerous flowers borne on a swollen and more or less 

 flattened receptacle.] 



ii. Sketch an isolated ray floret, shewing 



a. corolla ; 



b. bifid stigma ; 



c. ovary. 



iii. Shew on a sketch of an isolated disc floret 



a. ovary ; 



b. corolla with five lobes ; 



c. anthers, forming a tube standing above the corolla ; 

 from the middle of this tube the stigma emerges: it 

 afterwards opens so as to be obviously bifid, as may be 

 seen by comparing various florets. Slit open the corolla 

 with a needle and shew on a sketch that, while the 

 filaments are free, the anthers are all joined together 

 (syngenesious). Now slit open the tube of anthers and 

 shew that the style passes up inside the tube, thus sweep- 

 ing out the pollen which has been shed from the anthers, 

 which in this case open internally. 



To understand the adaptation for cross-fertilisation, 

 disc florets of various ages must be compared. 



[A comparative examination should be made of a floret 

 of Centaurea, Dandelion, or Groundsel, where the calyx is 

 very obvious, consisting of a number of hairs, and con- 

 stituting the "pappus," which afterwards forms the 

 " clocks " of the dandelion and groundsel.] 



