Although relatively uncommon, this phenomenon is reported almost every year. As most know, a corn plant has a monoecious flowering habit where the plant has both male and female flowers. What many may not know is that both flowers are initially bisexual. During the course of development the female components (gynoecia) of the male flowers and the male components (stamens) of the female flowers abort, resulting in tassel (male) and ear (female) development.
Now every once in a while, the upper flower that typically becomes a tassel instead forms a combination of male and female floral parts on the same reproductive structure. The physiological basis for the survival of the female floral parts on the tassel is likely hormonal, but the environmental “trigger” that alters the hormonal balance is not known.
It has been noted that can be varietal differences where different hybrids produce ears in the tassel and is linked to a particular set of genetics. Ear development in the tassel may also occur when the plant sustains hail or mechanical damage early in its development. Pollen shed would not have been affected, nor will yields be decreased as a result of this phenomenon.
For more information on the production and management of corn, please visit Manitoba Agriculture’s website at: http://www.gov.mb.ca/agriculture/crops/specialcrops/bii01s01.html