' WEATHERWAX: MORPHOLOGY OF FLOWERS OF ZEA Mays’ 137 
seem to be smaller and less developed than those of the aborted 
flower. This question will, however, bear further investigation. 
POLLINATION 
An unusually large number of interesting correlations are 
found between structure and function as applied to pollination. 
Practically the only means of pollen transfer are gravity and the 
wind. A few insects may work upon one or the other of the 
inflorescences, but none have been observed that find it profitable 
to visit both. 
The most noticeable correlation, and one that sheds much light 
‘upon the probable course followed in the development of monoe- 
cism, is in the position of the male inflorescence above the female 
this tending to render functionless the ovaries in the tassel and 
the pollen in the lower inflorescence of the primitive ancestor of 
the maize plant. 
The pollen is fine and light and easily carried by the wind. 
Each individual grain is smooth and dry on the outside and not 
well adapted to adhering to anything except something of the 
feathery nature of the stigma. Thus a minimum amount of 
Pollen is lost by adhering to the leaves and stem above the female 
flowers. 
Of course much pollen is lost by any plant that depends 
upon the wind for pollination, but ample allowance is made for 
this in maize. Lazenby’s estimate for a dent variety shows that 
about 45,000 pollen grains are produced for every ovule; and 
Sargent estimates that the ratio is at least 9,000 to I. These 
figures are reported by Hunt (6, p. 146). Ina variety of popcorn 
that I have examined, the number of male spikelets produced is 
approximately the same as the number of female spikelets, the 
Variety having an average of three ears to the stalk. But each 
female spikelet produces one ovule, while the six anthers of a 
male spikelet produce no less than 15,000 pollen grains. Since 
Most varieties have a larger tassel and a smaller number of ears 
than this one, it is probable that this ratio of 15,000 pollen grains 
to 1 ovule is low enough. ie 
The idea is held by many that self-pollination 1s prevented 
by the shedding of the pollen before the maturity of the stigmas 
