Trees Have Flowers? Who knew?

Yes, they do. They are vascular plants, just like garden plants, and they need flowers to produce seed for the next generation. Whether a tall pine or a little striped maple, all trees have flowers. Some trees have flowers with both male (pollen) and female reproductive parts in the same flower (called perfect flowers), and some trees have two different kinds of flowers (imperfect).

Trees that have two different types of flowers, but on the same tree, are called monoecious. If it takes two different trees (some holly trees, for example) they're dioecious. Obviously, what kind of flowers a tree bears, and whether both sexes are present on a tree, affects how selective tree breeding is carried out.

The Pines

The flowers of pine trees (in Ontario, white pine, red pine, pitch pine, and jack pine), are very tiny. They are found in cones, with each cone bearing organs of one sex only. Both sexes are on the same tree. The male cones cluster at the base of new spring growth, and they disintegrate after the pollen is released. The female cones are at the tips or sides of the new growth, and take two years to mature.

Red Pine Cone Red Pine
Copyright © 2001 Kathie Brosemer

The Spruces

Spruce tree (white spruce, black spruce, red spruce) flowers are similar to the pines, with both sexes on the same tree but in separate cones. Spruce cones mature in one season, and hang down from the branches.

The Poplars

Ontario's poplar trees (trembling aspen, largetooth aspen, balsam poplar, and eastern cottonwood) have flowers of only one sex on each tree. The flowers are very small, with several flowers arranged along a stem to form clusters that droop from the branches. Flowers appear before the leaves in springtime.

The Walnuts

Walnut (black walnut and butternut) flowers are of one sex but both occur on the same tree in separate clusters. The male flower cluster is an unbranched stem arising from lateral buds, with short spikes of from two to ten flowers attached along the length of the stem. The female flowers are near the end of the twig, individually or in twos and threes. They face the sky until the developing fruit gets heavy and pulls them over.

The Birches

Ontario's birch trees (white birch, yellow birch, black birch, grey birch, Alaska birch) have flowers of only one sex in a cluster, but both types of clusters occur on the same tree. Each cluster has stalkless flowers in tight spacing on a flexible stem. The male flower clusters appear in late summer before leaf fall, and remain throughout the winter before unfolding in springtime.

The Oaks

Oak tree (white oak, swamp white oak, chinquapin oak, chestnut oak, bur oak, red oak, black oak, and pin oak) flowers appear on the same tree, male flowers in clusters and females solitary or in small groups. They appear just after leaves unfold.

The Maples

Ontario's native maple trees (sugar maple, black maple, silver maple, red maple, mountain maple, striped maple, and Manitoba maple) have very diverse flowers. Some have only female reproductive parts, some have male only, and some are perfect (both sets of organs in the same flower). There may be different types of flowers on the same tree, and different types may occur in different stages of a tree's life cycle. Some flowers produce nectar and are insect-pollinated, some are wind-pollinated, and some are intermediate forms to take advantage of whatever pollinators are available.

The Ashes

Ash trees (white ash, blue ash, red ash, and black ash) have small, dark flowers arranged in compact clusters. The male and female organs are usually in different flowers and usually on different trees, the exception is the blue ash which has perfect flowers. They have no petals and tiny or missing sepals.