drous corn would yield largely hy- 
brid seed — each little corn embryo 
having two parents; while in a field 
of synacmic corn, a large proportion 
of the plants would be self-pollinated, 
unless there were strong winds. Ac- 
cording to some authorities, a large 
part of the cultivated corn of the 
United States belongs to this latter 
type; and as seed corn is generally 
selected on the basis of looks rather 
than of ancestry, the synacmic char- 
acter tends to decrease the yield. 
The introduction of proterogynous 
and proteran drous races will promote 
more cross-fertilization and thus tend 
to increase the yield. 
The proterogynous corn now 
growing in the Garden was secured 
through the kindness of Mr. G. N. 
Collins, botanist, crop acclimatiza- 
tion and adaptation, Bureau of Plant 
Industry, U. S. Department of Agri- 
culture. In Circular 107 of this 
bureau, he gives a detailed account 
of its characteristics and its probable value as plant-breeding 
material. Proterogynous varieties of corn are rare, although, as 
Mr. Collins states, there are reasons for believing that the more 
remote ancestors of maize, which are said to have had perfect 
flowers, were proterogynous. The so-called primitive varieties 
of maize from South and Central America tend to be proteran- 
drous. Perfect flowers are not infrequently found among the 
male flowers of the tassel and less commonly on the ear. Pod 
corn, a type in which each grain is enclosed in a separate husk, 
is generally rich in perfect flowers, and this peculiar variety 
(also now growing in the Garden) has often been looked upon as 
the nearest approach to the wild condition, although it itself is 
probably of comparatively recent origin. 
Fig. 3. T assels and ears from 
nearly sterile maize plants 
isolated from inbred strains 
(after E. M. East). 
