Smartweed - Native or Alien Type

Asked June 9, 2017, 6:53 PM EDT

This sprang out of my echinacea plant. I know its smartweed but I can't identify whether its the native variety or not. Please help.

Anne Arundel County Maryland smartweed native or alien smartweed

3 Responses

There are multiple types of smartweed. While this looks like it could be Pennsylvania smartweed, (Polygonum pensylvanicum or Persicaria pensylvanica), we are not certain and our natives specialist is out today.

In the meantime, take a look at this page from the Maryland Biodiversity Project for clues to drill down which one it may be: https://www.marylandbiodiversity.com/viewChecklist.php?family=?Polygonaceae

If you need an absolute definitive reply, let us know and we will run it by our specialist.

cm

cm,

Please run it by your specialist to determine the definitive answer and can you please include the characteristics that allowed the specialist to make the determination.

I request the definitive reply because I am a Maryland Master Naturalist and Tree Baltimore Weed Warrior. I am often in situations where I need to make a determination on whether a plant is native, alien, invasive, etc. and why. Since there is loads of smartweed around, I would like to be able to determine which are the natives, which are not, and pass that knowledge on to others.

Thank you!

Our specialist responds:

"Polygonum persicaria. This is one genus, or two now, where they keep changing the names and are doing still more research. What I once knew as P. persicaria is now Persicaria maculosa. Here’s a great webpage that describes why, and all seems to be very up to date: