COTTON THISTLE 



39 



chaffy bristles. The tube is 10-12 mm., and honey rises in the cylin- 

 drical throat 3-4 mm. This is divided above into 5 linear segments 

 6-8 mm., which continue to be straight. The length of tube does not 





HT1 



COTTON THISTLE (Onopordon Acanthium, L.) 



prevent honey being reached, and is due to the development of the 

 involucre which protects the buds, and makes the heads conspicuous. 

 They bend outwards more and more. The branches of the style are 

 closely parallel 3-4 mm., and have wart-like knobs on the outer margin. 

 In the second stage (hermaphrodite) they turn outwards and are 

 accessible to insects. There is a ring of short hairs i mm. below the 



