IV.] ARALTACE.e, CQRNACE^. 107 



very different. In the Umbellifers the honey, being 

 secreted on an open disk, is therefore open to 

 all insects. Though the tubes of the florets of the 

 Composite are short, still the honey is not quite so 

 accessible as in the UmbeUifers. H. Miiller gives the 

 preceding table, which brings this out very clearly, 

 and which also shows the care and perseverance with 

 which he carried on his observations. 



Thus, then, while in Centaurea, out of every 100 

 insects by which the flower is visited, no less than 58 

 are bees, 27 are butterflies or moths, 12 are flies, and 

 only 2 belong to other groups ; in the common 

 Carrot on the contrary, where the honey is quite 

 exposed, 13 in a hundred only are bees, 3 are butter- 

 flies or moths, 31 are flies, and 52 belong to other 

 orders. If a flower with a longer tube than that 

 of Centaurea had been selected for comparison, the 

 difference would have been even more striking. 



ARALIACEA 



The only European species belonging to this order is the Common 

 Ivy (Hedera helix). It is proterandrous, and is much visited by flies and 

 wasps. 



CORNACE^. 



This order contains one British genus, Cornus, with two species, C. 

 suecica the Dwarf Cornel, and C. sanguinea the Common Cornel. The 

 two species are very unlike ; C. suecica being a low herb with minute 

 flowers, which, however, are surrounded by four lar(i;e, white bracts, 

 which look like petals, and thus give the whole umbel the appearance 

 of a single flower. C. sangitinea is a shrub which attains a height of 

 five or six feet. The honey is secreted from a fleshy ring at the base 

 of the pistil ; it is accessible to all insects, and is much more visited 

 by flies than by bees. The anthers and stigma mature simullan£Qusly. 



