Soybeans are known to exhibit a high degree of flower abortion . Schaik and Probst (1958) noted that a large number of flowers open but drop off without ever forming pods . They also noted definite physical differences between shed ovules and viable ones.
Hallman, L. L. and Edwards, L. H.
"Research Notes: Pollination study on three varieties of soybeans using honeybees and leafcutter bees,"
Soybean Genetics Newsletter: Vol. 8
, Article 33.
Available at: http://lib.dr.iastate.edu/soybeangenetics/vol8/iss1/33