Id this weed

Asked September 18, 2019, 1:13 PM EDT

Please id this weed. I think it is invasive. It grows from a central root and spreads along the ground. It gets to about 3 ft tall. It is intertwined with shrubs I planted last year. All I can think to do is pull it. Thanks.

Howard County Maryland plant identification

3 Responses

Hi - This is a type of smartweed (Persicaria sp.). We have several species of Persicaria in Maryland; some are native plants, some are not. https://www.marylandbiodiversity.com/viewChecklist.php?genus=Persicaria
Based on the flowers and leaf characteristics I can see in your photo, this looks like it might be the native Persicaria sagittata.
https://www.marylandbiodiversity.com/viewSpecies.php?species=3558
If you don't want it, you can pull it out before it disperses seeds.

More concerning is that there is Japanese stiltgrass in your photo as well. Japanese stiltgrass is an invasive species and a very aggressive spreader by seeds. It can be difficult to manage. It is an annual plant, so a key to its management is to remove it before seed dispersal. Seeds can persist in the soil for 5+ years. Here is more information about it and what you can do. https://extension.umd.edu/hgic/topics/japanese-stiltgrass

Christa

I agree with your id.
The USDA plant profile indicates no value of this plant to human or animal or insect.
However I have been battling the stiltgrass (which you id) for years. This plant has deeper roots than stiltgrass. It seems to grow well with the stiltgrass. I wonder if this plant can help mitigate runoff.Not ideal but if it can grow with stiltgrass....

Any plants covering the ground, especially deep-rooted ones, will help to mitigate runoff, at least to some extent. We do often see other species of smartweeds growing alongside Japanese stiltgrass. They prefer a similar type of habitat.

If runoff and erosion are persistent problems for you, you might want to explore some of the options and resources on our stormwater management page. https://extension.umd.edu/hgic/topics/stormwater-management

Christa