140 CONVOLVULACE&. [CHAP. 



far at least as we know, is fertile with the pollen of 

 any other flower belonging to the species. Other 

 species are generally fertilised by insects, but in their 

 absence perform this office for themselves ; while 

 lastly, some species, such as Lithospermum arvense, 

 and Myosotis intermedia, habitually fertilise them- 

 selves. Again cross-fertilisation is secured in Pulmo- 

 naria by dimorphism ; in Echium and Borago by 

 proterandrousness (if I may be permitted to coin the 

 word) : in Symphytum and Anchusa, by the projec- 

 tion of the stigma beyond the stamens ; in Lithos- 

 permum and Myosotis, by the narrowness of the 

 flower tube. 



CONVOLVULACE.E. 



The well-known Convolvulus and the singular little 

 Dodder (Cuscuta) are the only British genera belong- 

 ing to this family. 



Cuscuta is a leafless, annual, parasitic plant, with 

 thread-like stems. The flowers are small, nearly 

 globular, and grow in lateral heads or clusters. One 

 species attacks the clover, and is sometimes sufficiently 

 abundant to do much mischief. 



We have in England three species of Convolvulus 

 C. arvensis, C. sepium y and C. soldamlla. 



C. arvensis being melliferous and slightly sweet- 

 scented, is much visited by insects. The honey is 

 situated below the bases of the stamens, which are 

 somewhat flattened and bent inwards, so that the 

 insect can only reach the honey by pressing its pro- 

 boscis down between them. The stigmas and anthers 



