234 BOTANY. 



flower-clusters of this or that shape, all have reference to 

 pollination (i.e., the placing of the proper pollen upon the 

 stigma). The pollen-cells are dependent for transportation 

 to the stigma upon (1) the wind (anemophilous flowers); 

 (2) certain contrivances by means of which insects (or 

 rarely birds) are made to carry the pollen from anther to 

 stigma {entomophilous flowers) ; (3) the favorable position 

 of the anthers and stigmas, bringing the pollen in the 

 opening anther into contact with the stigmatic surface 

 {autogamous flowers). 



497. The grasses and sedges, and the oaks, beeches, 

 chestnuts, walnuts, birches, and their allies, and a few 

 others, have wind-pollinated flowers. In these the pollen 

 is produced in great abundance, and the flowers are mostly 

 small, regular in form, simple in structure, uncolored, and 

 destitute of nectar (honey). The pollen-bearing flowers 

 are always in clusters which are exposed to the wind, as 

 in grasses at the top of the plant. 



498. A great number of plants have insect-pollinated 

 flowers; these are, as a rule, large, colored, sweet-scented, 

 and provided with nectar-glands; the nectar acts as a bait, 

 and the showiness and scent as guides,, to honey- loving in- 

 sects, which, by various contrivances in the flowers, are 

 made to come in contact with the anthers of one flower 

 and the stigmas of another, in the first dusting their bodies 

 with pollen, which in the second adheres to the stigmas. 



499. Large flowers are frequently solitary, but smaller 

 .ones are, as a rule, massed in clusters which thus become 

 conspicuous. In the golden-rods we have a good illustra- 

 tion of an extreme case of this kind, the individual flowers 

 being very small and inconspicuous, while the flower-clus- 

 ters of hundreds of massed flowers may be seen for a long 



