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When Do Birch Trees Pollinate?

By Teo Spengler
Birch flowers present as catkins.

Birches are termed "monoecious," meaning that the trees bear both male and female flowers on the same branch. Closely related to oaks and beech trees, each birch produces sufficient pollen to fertilize its female flowers in the springtime.

Male Flowers

Birch trees (genus Betula) have delicate leaves, papery bark and graceful silhouettes. Flowers appear in catkins. The male flowers -- erect staminate catkins producing pollen -- appear at summer's end at the tips of long shoots. They remain on the tree until spring pollination.

Female Flowers

Female birch flowers -- solitary pistillate catkins -- pass the winter enclosed in buds. They appear about the same time as birch leaves, presenting as short catkins of less than 1 inch on short shoots. Each catkin contains three flowers.

Pollination

In the spring, the male catkins grow and change color. When they are several inches long and a purplish yellow hue, they shed pollen for three to five days. The female flowers become receptive just before the male flowers on the same tree shed pollen.

 

About the Author

 

Teo Spengler is a docent with the San Francisco Botanical Garden and a staff writer with Gardening Know How. She has written hundreds of gardening and plant articles for sites like eHow Gardening, Gardening Know How and Hunker. She holds a JD in law from U.C. Berkeley, an MA in English and an MFA in Creative Writing.