Ask Mr. Smarty Plants

Although for the majority of plants (the hermaphroditic ones) sex determination is not a consideration, how is sex determined for the monoecious and the dioecious ones? As it turns out, there are several different strategies and all are genetic. In monoecious plants the incipient flowers begin with both pistlls and stamens but the sex determination genes (usually several different genes) cause the arrested development of the pistils in the male flower and the stamens in the female flowers. The level of gibberellin (a plant hormone) appears to be important in determining which type flower (staminate—male or pistillate—female) is produced. Exactly how it does this is not yet precisely known.

Some, but not all, dioecious plants have one pair of chromosomes that are not identical that are associated with determining the sex of the individual plant. This resembles the situation in mammals where males are XY and females are XX. For instance, Silene latifolia (bladder campion) has 24 chromosomes per cell. Twenty-two of these are autosomes (non-sex chromosomes) but two of these are sex chromosomes with XX individuals making female flowers and XY having male flowers. Other dioecious plants don't have a pair of visibly different chromosomes, but that doesn't necessarily mean that one pair of chromosomes might not be the sex chromosomes.

So, now for the answer to your specific question as to whether the plants from your one fruit will be all females or all males—I don't know for sure, but I suspect it will a mixture of males and females.

First, I could find no information about whether D. texana has visible sex chromosomes. I only know that it is dioecious. If it does have sex chromosomes, the female tree that produced the fruit had ovules with one X chromosome and the male tree that produced the pollen would have pollen grains with either an X or a Y. It would depend on which type of pollen grain (with either an X or a Y) fertilized the ovule as to whether the resulting plant would be female (XX) or male (XY). Each of the seeds in the fruit you planted would have been fertilized by a different pollen grain. Assuming that pollination is random, it isn't likely that your six seedlings are all males or all females.

Diospyros texana

Diospyros texana