Sexual Differentiation in Monoecious plants with unisexual flowers In monoecious plants having unisexual flowers (eg _Zea Mays_ , _Ricinus Communis_ etc), there must be some mechanism as to produce two sexually distinct flowers from the same genotype. Since both the type of flowers are placed on the same plant, the genetic constitution of the cells of both the type of flowers will be similar. **What is the mechanism by which the development of two sexually distinct flowers is carried out in such plants?** Is the mechanism similar to the mechanism for differential gene expression in case of embryonic development (Homeobox genes)? And moreover, **is the genetic constitution of the pollen produced by the male flower similar to that of the egg produced by the female flower, with respect to the composition of autosomes and allosomes (if any)?**

I will be able to answer only a part of the question.

_Sex determination in Zea Mays_

Initially, all the flowers in the plant are perfect, ie they have both the male and the female flowers. This is followed by abortion of stamen or pistil resulting in unisexual flowers.

Which part of the flower undergoes abortion is determined according to the location of the flower. The florets in the tassel undergo the suppression of the pistil primordia resulting in staminate flowers, while the florets in the ear undergo suppression of stamen primordia resulting in female flowers.

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The hormone Gibberelic Acid seems to play a role in sex determination.

Source and other useful links :

1. Sex determination in Plants by CC Ainsworth.

2. Sex chromsomes in flowering plants

3. Sex determination in monoecious and dioecious plants

4. The sex determination process in maize