Many ornamental plants are chosen for use because of their colorful fruits. Red holly berries, orange pyracantha berries, and white snowberries are just of few examples of the color that ornamental fruits bring to the garden. These plants are also attractive to 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 plants have perfect flowers. Roses and viburnums are examples of perfect flowered plants. This means that each individual flower has both male and female parts; stamens, which produce pollen, and a pistil, which contains the ovary(ies) which will produce the seed and hence the fruit. This makes self-fertilization possible.

Monoecious plants are also capable of self-fertilization. Unlike perfect flowered plants, monoecious plants have two types of flowers -- male (staminate) and female (pistillate). Both flower types occur on the same plant. Birches and pines are examples of monoecious plants. In either perfect flowered plants or monoecious plants, pollen is easily carried to the stigma of the same flower or of the female flower of the same plant by insects, birds, or wind.

In dioecious plants, pollination is not so easy. Each plant has only male or only female flowers, so if a particular plant is the only one of its species in an area, pollination is impossible and no fruit will result. Hollies and yews are examples of dioecious plants. In order to ensure a good fruit set on these plants, male and female trees must be grown within a reasonable distance of each other. Although they need not be grown side by side, the closer the male and female plants stand, the better the fruiting which may be expected. One male plant can serve as a pollinator for several female plants. It is also possible in some cases to graft a male branch onto a female plant to enable pollination to occur.

Identification of sexes in dioecious plants is not difficult, though sometimes it may require more than the naked eye to see the tiny flower parts involved. Male flowers lack stigmas or have undeveloped stigmas, and will have stamens. Female flowers have stigmas but not developed stamens. Obviously, a plant with fruit will be a female, but a fruitless plant is not necessarily a male. The plant may be fruitless due to lack of pollen or because environmental conditions were not suitable for pollination. Check the flower structure to be sure of the sex.

Occasionally the sex of dioecious plants is important because a lack of fruit is desired. Fleshy fruit-like ginkgo seeds have an objectionable odor and mulberry fruits can litter the ground. In such cases it may be very useful to plant only male trees, as a female tree could receive pollen from neighboring sources resulting in the undesirable fruit.