US: "Some of those tall, beautiful sunflowers are no friends to bees"

The year of the sunflower, as decreed by the National Garden Bureau, is upon us, and the big summer bloomers are seemingly everywhere. Even the shortest suburban walk provides proof of the enduring popularity — and great diversity — of the annual sunflower. But for all the variation available to American gardeners, most of these plants likely share one trait: blooms that have no pollen.

Most sunflower seed sold for ornamental use in the United States produces pollenless flowers. Unbeknownst to many consumers, this has been the case for decades. Pollen is the tiny yellow grain that holds sunflower sperm. High in protein, pollen is critical to the survival of native and domesticated bees and floral flies.

Gretchen LeBuhn — a biology professor at San Francisco State University, coauthor of “The Bee-Friendly Garden,’’ and director of The Great Sunflower Project, a long-running citizen-science initiative that tracks pollinator visits to backyard flowers — explains that bees can’t raise offspring on pollenless blooms.

A US Department of Agriculture report on 2019 floriculture crops shows that ornamental sunflowers grown in the United States are a $9 million industry — a low estimate because this doesn’t include blooms grown by smaller producers and sold, for example, at farmers markets. Globally, about 1 billion ornamental sunflower seeds are sold each year, according to an estimate provided to the Globe by American Takii, the daughter company of Takii Seed, based in Japan.

John Dole, a professor of horticulture at North Carolina State and the executive adviser for the Association of Specialty Cut Flower Growers, estimates that 90 percent of the ornamental sunflowers grown commercially in the United States are pollenless. That percentage is likely higher still when it comes to the hundreds of thousands of stems harvested weekly in Ecuador and Columbia and imported through Miami.

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