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When do birch trees bloom?

Updated April 14, 2018

Not every spring wild flower fits well into a bouquet. The slender birch tree offers both male and female flowers in the form of catkins. Birch pollen fertilises female flowers about the time the birch leaves open.

Identification

The birch is a hardy pioneer tree, among the first to colonise a cleared or burnt-out area. Its bark is papery and its leaves delicately toothed. Birches are monoecious: they carry both male and female flowers on the same branch.

Male Catkins

Male flowers appear on birch trees at the end of summer as clusters of erect catkins. Initially about 2 inches long, the green catkins overwinter on the tree, growing longer in the springtime. When the male catkins "bloom," they turn purple and release pollen to fertilise female flowers.

Female Catkins

Female birch flowers also pass the winter on the birch tree, but they are enclosed in buds. In late May or early June, they emerge from the scaly buds to "bloom" as short catkins. Female birch flowers are receptive shortly before nearby male flowers release pollen.

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About the Author

From Alaska to California, from France's Basque Country to Mexico's Pacific Coast, Teo Spengler has dug the soil, planted seeds and helped trees, flowers and veggies thrive. World traveler, professional writer and consummate gardener, Spengler earned a BA from U.C. Santa Cruz, a law degree from Berkeley's Boalt Hall, and an MA and MFA from San Francisco State. She currently divides her life between San Francisco and southwestern France.