Oriental Lady’s Thumb – a kind of Smartweed – is a fairly new invasive here at the farm.  We have several other species of Smartweed, and this one looks similar to Pennsylvania Smartweed (Persicaria pensylvanica), which is common, and not invasive.  So we didn’t really notice Oriental Lady’s Thumb until it began to spread on two of our trails in 2017.  By 2019 it was clear that it was a problem.

 

It’s a sprawling annual that produces many seeds and seems to prefer damp, shady, disturbed places.  Fortunately it seems to stay on the trails, and doesn’t invade the undisturbed areas nearby.

 

The easiest way to tell it apart from other similar Smartweeds is to look at the sheath at the base of the flower stalk (the ocreola).  Several long bristles stick out from the edge of the sheath.

 

We mowed the plants in August 2019, hoping that would keep them from producing seeds.

 

But in 2020 it was back – somewhat reduced, but still a problem.

 

So we’re trying a different scheme.  We pulled all the plants we could see in late summer of 2020.

 

Pulling the plants looked good for the rest of that year, but the next year they all came back.  We decided that we just didn’t have the hours it would take to eliminate all the plants and seeds, so we let them go and tried to ignore them.

Now, 4 years later, we still have the plants, but less dominant, and more just a part of the disturbed areas – mostly in the mowed paths.