Ailanthus altissima
Bisexual flowers that contain both male and female sexual organs are said to be perfect. Angiosperms may also have imperfect flowers, on the same or different plants, that lack one or other type of sex organs. Sometimes, as in the tree of heaven ("Ailanthus altissima") and the European ash ("Fraxinus excelsior") the panicles can produce different mixtures of functionally unisexual and functionally bisexual flowers on the same or different trees.