Asked if he’s seen garlic mustard growing in Beltzville State Park where he works as an environmental education specialist, Rob Bergstresser answers in the affirmative.

“Garlic mustard is one of the most common, and most widespread invasive species in the Northeast,” Bergstresser said.

It’s no surprise that he’s seen the extremely aggressive invader that chokes out native plants in many places other than the park near Lehighton.

“In certain areas, I’m definitely seeing more, especially after the mild winter we had this year. In many areas, I’m seeing more mature plants than in previous years,” he said.

Chances are you’ve seen the nuisance plant as well. The species, which originated in Europe, grows along the sides of the roads, in yards and in forests.

“Because it spreads so easily, it will continue expanding its range in the U.S.,” said Bergstresser, who will lead a May 19 walk at the park to show participants both native and invasive species.

Garlic mustard has white flowers and triangular or heart-shaped leaves, and can grow as tall as 3 feet. When crushed, its leaves smell like garlic.

In recent years, groups have gathered for “garlic mustard pull” events at state parks across the commonwealth.

Some gather it for its food and medicinal purposes.

“They absolutely overwhelm and out-compete our native plants for habitat, sunlight and vital nutrients,” Bergstresser said.

It also has chemicals in its taproot system that can alter the chemical composition of the soil. That, he said, can damage the vital underground “network” for fungus - called mycorrhiza - that connects trees within our native forests, eventually stunting the growth of many vital native trees.

“Once garlic mustard gains a strong foothold in an area, it’s tough to remove. It’s also one of the first plants to bloom in the spring, and its seeds spread very easily.”

That’s why Bergstresser advises caution when trying to get rid of the plant.

“In small sections, sometimes it’s best to just let them be, rather than risk spreading more seeds.

“Garlic mustard is here to stay, like so many other invasive species, so it’s not going anywhere no matter how much we try and eradicate it,” he said.

Folks can attempt to control garlic mustard but Bergstresser said it is only advisable when the plant is in its first year and it is no higher than 8 inches.

Second year growth reaches up to 3 feet, and the plants become laden with seeds.

“The best time to pull would be in the early spring, before it starts to flower, and after it rains so that all of the taproot can be easily extracted,” he said. “It’s very important to immediately place it into a bag after pulling it, so that you don’t risk spreading any seeds. You need to be very persistent in areas where you plan on pulling garlic mustard. It can take several years to completely remove it from just a small area.”

The Nature Conservancy notes that the plant was introduced to North America in the mid-1800s for its herbal and medicinal qualities and for erosion control.

In its native European and Asian ranges, Bergstresser said garlic mustard is naturally controlled by native insects that feed on the plant. Those insects aren’t present in the United States.

Despite the problems it can cause, Bergstresser described garlic mustard as “delicious” when eaten in its early stages.

“There are many great recipes online,” he said.

He cautioned that once it is mature, it can contain slightly more toxins and must be cooked for a longer period of time.

As always, people should never consume anything that they cannot identify with 100% certainty.