If you had not heard of it before, you might never know what French broom is and the stress it puts on other plants.

Still, seeing firsthand the havoc it can create provided a group of 16 Pacific Union College biology students a real-world lesson during a Land Trust work party this spring.

“Real-world experience is critical to having a complete understanding of the threats that invasive plants cause,” said PUC Associate Professor and Biology Department Chairwoman Aimee Wyrick-Brownworth.

French broom is a shrub believed to be first introduced to California in the mid-1800s when people planted them as decoration in their garden. The woody, green stems and small yellow flowers can get big fast, however. So fast that, according to the California Invasive Plant Council, it can reach 4.5 feet in two growing seasons.

And while it might seem like an innocent landscaping shrub, it can soon overwhelm everything around it, making the term “invasive” a fitting one.

“This workday opened my eyes to how densely French broom can crowd an area and spread,” said Gabe Ceniceros, a junior biology major. “After the workday, I felt like I could see French broom everywhere I looked.”

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“French broom takes over the habitat of other native plants because it has no natural herbivores,” said Wyrick-Brownworth. “Without the threat of getting eaten, the plant can focus more of its energy on growing and reproducing.”

Once French broom starts pushing out native plants, the animals that rely on those native plants in turn have less food as plant diversity is reduced.

Land Trust of Napa County continually fights the battle with French broom and other invasive plants on its preserve properties, sometimes over the course of several years. One of our most recent property transactions, a 58-acre property acquired last year that abuts our 3,000-acre Wildlake Preserve, had a need for French broom removal, and with Pacific Union College nearby, the collaboration came easily.

“We needed a big area for the group. And with French broom taking over in certain pockets, this property was a good choice,” said Erin Erickson of the Land Trust. “They did a really good job of pulling out the whole patch.”

Jorgen Gulliksen is the communications associate at Land Trust of Napa County.

The Land Trust of Napa County is a nonprofit dedicated to preserving the character of Napa by permanently protecting land. In its 41-year history, the Land Trust has protected more than 65,000 acres of land, more than 1 2 percent of Napa County.