Most damp partial sun to shady areas are filled with smartweed now. Plants have always been there but the fall weather makes them more prominent. Some have white flowers while others have pink. This herb has almost as many uses as there are different species of it. About 75 different Polygonums reside in North America and many of them thrive in North Carolina.
Plants usually have variegated leaves and branch freely. Most leaf blades have a purplish blotch on them. Young stems creep at first, and then become semi-erect. Sometimes brittle stems are swollen where leaves attach, so they have a jointed appearance.
Elongated pointed leaves have very short stalks, a wavy but not toothed edge and are fringed with hairs. Flowers reside at the stem tips and are small and in vertical clusters called racemes. These inflorescences usually droop at the ends.
Smartweeds can be found in the same places every year, but few species are perennials. They reproduce by seed. Each plant can produce more than 3000 seeds. Some species even thrive in standing water.
This common but unusual herb is in the buckwheat family. I wouldn’t recommend using it in a batch of pancakes though. It is edible but better used as an accent and not the main course. Most species have a strong peppery taste. It kind of creeps up on you and gets stronger the longer you keep it in your mouth.
Some types, like the lady’s thumb smartweed are far less peppery. Others, such as the very similar looking Pennsylvania smartweed (Polygonum pennsylvanicum) can have a taste so biting that wildlife often won’t eat it unless no other vegetation is available. Still other species like the water pepper are even hotter than habaneros.
In small quantities smartweed makes a great pungent seasoning. Use it sparingly in salads and soups like you would cayenne pepper. Cooking dulls some of the fire. Always make sure to wash it well first, especially if you collected it from a wet swampy area. Also, keep in mind that if you are pulling weeds in an area with a lot of smartweed, you should wash your hands thoroughly before touching your eyes. You might not know the species.
Ridding your property of this weed might take a while. Smartweeds are prolific seed producers. Treating aquatic areas can be costly and difficult. In gardens, smartweed attracts undesirable insects that damage crop plants. It also grows fast, so remove it when you first identify young seedlings.
Smartweed has been used medicinally for many ailments including diarrhea, cleaning wounds, heart ailments, stomach aches, sore throats and stopping bleeding. Leaf teas are often the preferred administration method. Leaves have also been used to treat hemorrhoids.
All Polygonum species contain large amounts of vitamin K like many wild and domestic greens. Vitamin K helps the body make blood clot. Warfarin (Coumadin) is a common medicine used to thin the blood, and some sources say smartweed might decrease the effectiveness of warfarin. Therefore, it’s important to keep this in mind if you are on this medication.

A thick stand of smartweed in flower

Patch of smartweed within a stand of white clover

close-up view of Pennsylvania smartweed

Ted Manzer teaches agriculture at Northeastern High School.