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, a8 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 
