394 THE SEA SHORE 



coloured petals that are . more easily seen by night ; they also 

 evolve a powerful scent to aid the insects in searching them out. 



It will be seen that the economic relationship existing between 

 flowers and insects is a mutual one, the latter visiting the former 

 in order to obtain food, while the former derive in return the 

 advantage of a direct transfer of pollen from flower to flower. 



It is a well-known fact that the self-fertilisation of a flower 

 often results in the development of very weak seedlings as compared 

 with those that are produced by crossing ; and it often happens that 

 the pollen of a flower is incapable of producing the least effect when 

 deposited on the stigma of the same bloom. In some cases the 

 contact of the pollen of a flower with its own stigma will even 

 act as a poison, causing the whole to shrivel and die ; and truly 

 wonderful are the varied means by which flowers contrive to secure 

 a cross-fertilisation. It is here that the work of the wind and 

 insects proves so valuable to flowers ; but, in addition to this, a very 

 large number of flowers are absolutely incapable of self-fertilisation, 

 for the anthers and the stigma are not mature at the same time, 

 or they exist in separate flowers, either on the same plant or on 

 distinct plants of the same species. It is most interesting and 

 instructive to study the many contrivances by which flowers 

 compel certain insects to convey the pollen exactly in the way 

 that best serves their purpose, sometimes even entrapping them, 

 after they have been allured, and not allowing them to escape 

 until they are thoroughly dusted with the pollen which they are 

 required to convey; but it is hardly our province to enter more 

 fully into this matter in these pages. 



An examination of the grasses will show at once that they are 

 adapted for fertilisation by the wind. The flowers produce no 

 nectar; and, consistently, develop no bright petals and evolve 

 no odours to attract insects. On the other hand, their anthers 

 produce abundance of lightly- adhering pollen, and are mounted 

 on long filaments which hold them well exposed to the wind ; and 

 the stigmas are well adapted for catching the scattered grains, being 

 long and protruding, and often covered with sticky hairy or 

 feathery appendages. 



Although the flowers of grasses are generally wanting in attrac- 

 tive colours, the clusters of blossoms are often very graceful and 

 pretty, especially when the large anthers, covered with bright-yellow 

 pollen, dangle in the breeze. 



We will now briefly describe the principal British grasses that 



