It Grows a Mile a Minute

Mile-a-minute weed (photo by Kate St. John)
Mile-a-minute weed (photo by Kate St. John)

19 August 2015

If you ever see this plant, eradicate it!

My first encounter with Mile-a-minute weed was a decade ago in the Laurel Highlands when a small patch of leaves caught my eye.  Such perfect triangles! I didn’t know the plant but if I had I would have uprooted it.

Mile-a-minute weed (Persicaria perfoliata) is an annual, trailing vine, that thrives in sunlight and can grow 6 inches a day(!).  It has triangular leaves and perfoliate cups at the stem joints, called ocreae, where it produces flowers and fruit.  Notice the recurved thorns on the stems and on the underside of the leaf veins that give it this alternate name: Devil’s tear-thumb.

Mile-a-minute stem (photo by Kate St. John)
Mile-a-minute stem (photo by Kate St. John)

Persicaria perfoliata tried to invade North America several times but didn’t take hold until the late 1930s when it charmed a nurseryman in York County, Pennsylvania. He received it unintentionally in a shipment of seeds, was fascinated and allowed it to grow. By the time he realized his mistake it was too late.  Birds and animals love the fruit and spread the plant. 

Mile-a-minute now swamps southern Pennsylvania, Maryland, and parts of the Mid-Atlantic and New England.  It has spread more than 300 miles since it left York.  Click here for the map.

If you think you’ve found Mile-a-minute weed, check a few things before you pull.  Does it have perfect-triangle leaves?  Does it have perfoliate cups at the stem joints? Does it have thorns?  If so, you’ve found the bad stuff. 

Before you put on long pants, long sleeves and gloves to pull it out there’s one more question to ask: Does it have fruit? If so, be very careful not to spread the seeds while you pull — collect them first. This annual plant can only return next year if the seeds spread.

I found a fruitless specimen dying in Frick Park last weekend.  I had noticed it in July and was finally returning to pull it but, thankfully, park stewards had already dosed the area with therapeutic defoliant.  Good!  I administered the final blow and pulled it out.

(photos by Kate St. John and Wikimedia Commons)

6 thoughts on “It Grows a Mile a Minute

    1. Gindy, no it’s not the same as kudzu. But it has made an appearance in the South. See Art Gover’s comment below about mile-a-minute in North Carolina.

  1. I spent all weekend pulling these vines off of my shrubs! Last year was the first time I ever saw them. If there is any bright side to this, it means that the birds are still hanging out in the yard, enjoying the areas we planted as cover for them.

  2. Mile-a-minute (MAM) has been confirmed in western North Carolina, and the NC Dept. of Agriculture is coordinating suppression/monitoring. Matt Swain at Appalachian State was conducting research on the interaction of MAM, the biological control agent (an introduced weevil), and the native plant community.

    1. Art, thanks for the update. The maps I looked at must have been old. Alas! Bad news for N.C. … but the weevil sounds like a good idea.

Leave a Reply

Your email address will not be published. Required fields are marked *