Persimmon fruit trees are dioecious species, meaning that a tree will produce either male or female flowers. This differentiation is the key way to determine a tree's sex, save for the presence or lack of fruit development. This requirement calls for male and female trees to be planted in general proximity to one another to allow for cross-pollination and fruiting, usually at a rate of one male to eight female trees.
Rarely, male and female persimmon trees can possess perfect flowers with both male and female parts so they can self-pollinate. However, even in this rare instance only female persimmon trees can produce fruits. Persimmons begin to flower and fruit regularly at three to six years old. Before this, determining the sex of the tree is difficult if it's not labeled.
Look for male persimmon flowers in the spring that are clustered on the branches in groups of three and are immediately adjacent to a leaf axil.
Check for the size of male flowers looking for those that are 1/4 to 1/3 inches in diameter versus the larger female flowers that measure 1/2 to 3/4 inches in diameter.
Identify the unique male flower stamens protruding up through the center of the flower with 16 to 24 yellow to slightly green stamens arranged in two concentric rows. Female flowers sport just four to eight, shorter and less developed stamens.
Observe the lack of fruit development on mature trees over three to six years of age in the summer. Male trees will not develop persimmons after bloom, while female trees will.