Invasive plant found in St. Paul campus garden

The black swallow-wort could choke native plants if it’s not destroyed.

Invasive Black Swallow-wort plant has been identified on the grounds of the St. Paul campus. Plans for its removal have been made.

Image by Zoe Prinds-Flash

Invasive Black Swallow-wort plant has been identified on the grounds of the St. Paul campus. Plans for its removal have been made.

by Becca Shrake

It crept silently through the garden, hiding among the vast array of shrubs. Months passed and it continued to grow larger and stronger, threatening the lives around it.

The invasive black swallow-wort plant was identified a few weeks ago, entangled around plants in a garden on the corner of Gortner and Folwell avenues on the University of MinnesotaâÄôs St. Paul campus. If itâÄôs not eradicated, it could grow to cover acres of land, completely suffocating native vegetation.

Last fall, Hedera Porter, a University postdoctorate student, noticed the plantâÄôs shiny, dark green leaves in parts of an area known as the Display and Trial Garden.

Porter said she didnâÄôt know the black swallow-wort was invasive at the time, but kept a watchful eye on it. When it continued to spread its vines throughout the garden, Porter knew it didnâÄôt belong and reported it to the Minnesota Department of Agriculture.

Unfortunately, winter came and snow fell before the plant could be officially documented and it wasnâÄôt until a couple weeks ago that the department followed up.

Even though months had passed since the black swallow-wort first appeared, itâÄôs still early enough to nip it in the bud since it hasnâÄôt spread its seed yet, said Monika Chandler, who coordinates biological control programs at the Department of Agriculture.

âÄúRight now, itâÄôs so controllable,âÄù she said.

St. Paul gardeners will dig out the roots of the black swallow-wort. If the infestation were larger, theyâÄôd use an herbicide. 

The black swallow-wort is a type of milkweed native to areas in Europe and Asia, according to the departmentâÄôs website.

Now, the plant is abundant on the East Coast and has spread into parts of the Midwest.

Every now and then the black swallow-wort creeps up in Minnesota, Chandler said. The plant was eradicated five years ago in South St. Paul. But according to the Department of Agriculture, the St. Paul campus infestation is currently the only known infestation.

Black swallow-wort is not wanted here or anywhere in North America because itâÄôs not native and destroys the native plants, said Liz Erickson, the spokeswoman for the Department of Agriculture. But people are attracted to it because it produces a unique, pretty flower, she said.

The difficulty of the black swallow-wort is that it doesnâÄôt look dangerous, Chandler said.

âÄúItâÄôs difficult to get people to realize that something that looks so harmless can be dangerous,âÄù she said. âÄúIt looks so innocent.âÄù

At this time of year, the plant begins to produce seedpods, meaning seeds will soon spread elsewhere.

Finding the plant on the St. Paul campus was a blessing in disguise, Chandler said, because the people working there are educated about invasive species and knew what to look for.