no STELLATE, VALERIANE^. [chap. 



but the tube is rather shorter, and the honey in con- 

 sequence more accessible to bees. In our third species 

 again, L. xylosteum, the tube is still shorter, and the 

 flowers are regularly visited by flies and humble-bees. 



STELLATE. 



We have four British genera of this order, Rubia (the Madder), 

 Galium, Sherardia (Woodruff), and Asperula. 



The flowers are small, but in many cases rendered conspicuous by 

 association. Several of tie species are sweet-scented, and attract 

 insects by means of honey, which is either exposed on a flat disk (Rubia 

 and Galium), or contained at the base of a short tube (Sherardia and 

 Asperula). The stamens and pistil ripen simultaneously, and if not 

 visited by insects, the flowers fertilise themselves. The florets ol Rubia 

 peregrina are greenish ; those of Sherardia arvensis blue or pink ; the 

 others either white or yellow. Miiller calls attention to the influence of 

 colour in the case of Galium mollugo and G. verum^ which agree closely 

 in most points, but the former of which is white, while the latter is 

 yellow, which he says renders it much more attractive to small beetles. 



Fritz Miiller has described (Bot. Zeit. i865, p. 129) a very interesting 

 South American species of this group, Martha [Prosoqueria] fragrant, 

 in which the stamens are irritable, and when touched by the proboscis 

 of an insect, immediately explode, and throw the pollen on to the 

 insect, at the same time closing the entrance to the tube of the flower, 

 in which the pistil is situated, and thus preventing the possibility of 

 self-fertilisation. 



VALERIANEy9i. 



Of this family we have only one traly British genus, Valeriana, 

 though Centratithus ruber, having been long cultivated in gardens, has 

 become naturalised in some parts of England. 



The flowers of the Allheal ( Valeriana officinalis), though small, are 

 rendered conspicuous by association. They are mellifcious, and the 

 honey is accessible even to short-tongiTed insects, by \\Uich they are 

 much frequented. They are proterandrous. 



Valeriana dio'ca, while agreeing with the precedinc; as regards the 

 honey, is, on the contrary, generally dioecious, the male flowers being, 

 as usual, larger than the female, and, consequently, in most cases 

 visited first. 



COMPOSITE. 



This great group contains no less than forty British 

 genera, and a very large number of species. It 



