308 PLANT-LIFE 



" ripe " when a viscid substance is exuded at its sur- 

 face. It is in this substance that the pollen grains 

 germinate. The Plantains (Plantago, Plate LIX.) pro- 

 vide us with good illustrations of the principle just 

 described. The little flowers are arranged in spikes, 

 and open from the base to the apex. By the time the 

 stamens are conspicuously displayed at the base of the 

 spike, the stigmas associated with them have done duty 

 and withered. They benefited by the reception of 

 pollen from another plant, and while the lower stamens 

 are functional for the benefit of a different plant, those 

 at the apex of the spike are not ripe, but the stigmas 

 are receptive. The Bur-Reeds (Sparganium) , which grow 

 in ditches and slow streams, are anemophilous. The 

 flowers are massed in heads that have the appearance 

 of burs; hence the common name. The sexes are repre- 

 sented in different heads, In the Branched Bur-Eeed 

 (Sparganium ramosum) the upper flower-heads are com- 

 posed of male flowers, while the lower ones are female. 

 The female flowers mature first, and receive wind-borne 

 pollen from a different plant in which the males are ripe. 

 After fertilization, the stigmas wither and the ovules 

 begin to ripen. It is then that the male flowers open 

 and discharge pollen, which is drifted to a plant with 

 mature stigmas. Thus, cross-feitilization is assured. 



We ought not to conclude that wind-pollinated flowers 

 are utterly neglected by insects. They certainly offer 

 no honey, but insects are drawn to them by their 

 appetite for pollen. Insects are to be seen either col- 

 lecting or glutting themselves with pollen produced in 

 profusion by Grasses, Plantains, and Hazels, but any 

 service they give in exchange for what they get is 





