SOME ADDITIONAL NOTES ON POLLINATION 
OF RED CLOVER. 
L. H. PAMMEL AND L. A. KENOYER. 
' ■ ■ • : i-> ( . 
Many years ago Charles Darwin conducted some experiments 
to determine whether red clover is self fertile. This investi- 
gator found that when insects were excluded, reel clover did not 
produce a single seed, while flowers exposed to insects produced 
an average of twenty-seven seeds per head, The experiments 
of Darwin and many of the older investigators who conducted 
experiments with red clover were faulty since they did not re- 
lease the anthers from the keel. The experiments of Frandsen, 
according to Lindhard, 18 Waldron, 7 Kirchner, 4 Witte, 6 Fru- 
wirth, 3 Pammel and King, 11 Sirrine, 5 Beal, 9 Cook, 1 Shamel 12 and 
Bolley 13 confirmed the results of the work of Darwin. 19 These 
authors find that bumble bees and in some cases honey bees 
are the important pollinators. Several years ago H. S. Coe, H. 
D. Ilughes, L. H. Pammel, J. N. Martin and J. N. Westgate 
published a lengthy account of the pollination of the red clover.* 
The more important conclusions arrived at are given in the fol- 
lowing summary from the bulletin, “Red Clover Seed Pro- 
duction.” 
A study of the cytology of red clover flowers show T s that many 
of them contain infertile ovules. The percentage of infertile 
ovules is greater in the first crop than in the second crop. In 
the first crop many plants produce 100 per cent of infertile 
ovules, while in the second crop the percentage of infertility 
ranges from none to a high per cent. The percentage of infer- 
tile ovules in red clover is probably correlated with moisture 
conditions. 
The pollen grains of red clover are very sensitive to moisture. 
On account of this there can be little effective pollination when 
the flowers are wet. Germination of the pollen grains takes 
place only within a limited range of variation in the water 
supply. It is probably true that the only function of the stigma 
is that of supplying the requisite amount of water to the pollen 
for germination. 
*Red Clover Seed Production, Bull. U. S. Dept. Agr., Con.tr. Bur. PI. Ind., 
289 : 1 - 31 . 
