Many ornamental plants decorate gardens and landscapes with red, orange, yellow, blue, purple, gray, black and white fruits. These fruiting ornamentals are also a great attraction to wild birds. Unless the sex characteristics of the plant are known, however, the homeowner may be disappointed because there may be no fruit crop even though bloom occurs. Many species of plants such as roses and viburnums have perfect flowers.
Sexes are separate in some other plants.
Birches and pines are examples. In perfect flowered and monoecious plants, pollen is carried to the stigma of the same flower or of the female flower of the same tree by insects, birds or wind. In dioecious plants, male flowers appear on one plant and female flowers on another. Many homeowners complain that flowers do not set fruits on some of their trees and shrubs. In many cases, the reason for non-bearing is that those plants are dioecious.