FLOWERING PLANTS OF THE SEA-SIDE 393 



It will be convenient at this stage to refer briefly to the two 

 principal methods by which the pollen of flowers is transferred 

 to the stigmas for the purposes 

 of fertilisation, and to see how 

 various species are structurally 

 adapted to the means by which 

 the transfer is brought about. 



Speaking generally, we may 

 classify flowers into those which 

 are fertilised by the wind 

 (anemophilous flowers) and 

 those in which the pollen is 

 transferred by insects (entomo- 

 philous flowers). The former 

 offer no attractions to allure the 

 various forms of insect life. 

 They are, generally speaking, 



F.S 



FIG. 



277. EXPANDED SPIKELET OF 

 THE OAT 



G, glumes ; P.e, outer pale ; P.i, inner pale ; 

 A, awn ; F.S, a sterile flower. The stamens 

 and the feathery stigmas of the fertile 

 flower are also shown 



very inconspicuous, being of 

 small size and having no bright 

 corollas. None of them are 

 scented, nor do they produce the 

 sweet nectar that forms the 

 principal food of so many insects. Their anthers are borne on 

 long filaments, so that they are exposed freely to the wind ; and 

 they produce abundance of pollen to compensate for the very 

 wasteful method of wind-dispersion. The pollen, too, is not very 

 adherent, so that it may be readily carried away by the breeze ; 

 and the plants concerned often produce their flowers early in the 

 spring, before the leaves have appeared, thus giving the wind very 

 free play. 



Insect -fertilised flowers, on the other hand, are usually of 

 attractive appearance ; and, though often small and inconspicuous 

 individually, they are in such cases grouped together in more or 

 less showy clusters. They are also usually scented, and supply 

 nectar and pollen to the insects which they allure. Some are 

 fertilised by insects that fly by day, and these often close their 

 petals on the approach of night, thus protecting their pollen during 

 the period in which their fertilisers sleep. Others, fertilised by 

 nocturnal insects, always spread their petals during the night, and 

 generally protect their pollen from waste by sleeping throughout 

 the day. As a rule, too, these night-bloomers have large and pale- 



