Hi Nancy,

Thank you for contacting the UVM Master Gardener Program with your question about the Yellow Flag Iris. Your iris pictures do look similar to the Yellow Flag Iris and one photo in particular seems to show it growing by some water, but it is hard to tell from a photo. Have you tried identifying it with iNaturalist or another plant identification app? The seed pods are pretty distinctive if you can find one.

As you probably know, although they are very attractive (we have a few small clusters on our property), the Yellow flag Iris can be very problematic because the tubers can grow together in dense mats which can crowd out native plants. It is hard to remove because even little pieces of the root can grow into a new plant and many people have an adverse skin reaction when they touch it. In VT, the yellow flag iris is on a 'watch' list. According to Deb Heleba, 'a "watch list" is an unofficial, non-regulatory list of plants of known or suspected conservation concerns -- it basically means that the group of experts that advises the state has put a plant on their radar but its sale, movement, etc. is not yet regulated.' https://agriculture.vermont.gov/sites/agriculture/files/documents/PHARM/Plant_Pest/NoxiousWeedsQuarantine1.pdf

She also mentioned that it looks like there might be some night shade growing in with it - both of which are toxic to animals. She says if they are on your property and if you go ahead to try to remove them, use the management options listed at: https://vtinvasives.org/invasive/yellow-flag-iris -- making sure to wear proper clothing and gloves. Last of all, I have shared a similar link from Cornell if you want to compare resources. 

https://erie.cce.cornell.edu/resources/article-1-invasive-yellow-flag-iris

Thank you for reaching out.

Thank you. This is actually on State property in Bennington (where the courthouse is). They are growing in a little stream. I walk past this to get to the parking lot and since I know the yellow flag are invasive I wanted to check before I mention it to the groundskeepers.