Arlington County staff are asking for your help in stopping a new invasive plant before it becomes established. Have you seen evergreen, parsley-like leaves on the forest floor? They may be the evergreen winter foliage of plants in the genus Corydalis. Only two species are known to occur in this area of Northern Virginia. One is native and the other invasive. The invasive species, incised fumewort (Corydalis incisa), has been identified by the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service as a “high risk” invader, which means that it has the potential to both become widespread and cause a lot of damage.
Flowering begins in March, and at this time they are easy to tell apart by flower color. In the photo, the alien invasive (left) has purple flowers, and the native (Corydalis flavula) has yellow flowers. Plants produce mature seeds quickly, within two or three weeks of first bloom. Thus, timely location and identification of C. incisa right now will help keep its seeds from spreading.
Photo from Wikimedia Commons
Arlington County staff has had only a few observations of this plant in Arlington so far and has been able to treat them. The county wants to search more widely this spring and catch this plant before it becomes established.
Please be on the lookout for it and use iNaturalist to report sightings. To make good observational records:
- Take several photos that show the landscape around the plant, photograph a whole plant including flowers and leaves if they aren’t flowering yet, and photograph a whole, typical, undamaged leaf.
- Make comments that are explicit about the issue of intentional plant vs. weed vs. escaped, give a rough estimate of the number of patches and the area covered, and include any other comments you think might be helpful.
On private property, if you have permission, remove the plant, bag, and put in the trash. Touching the swollen seed pods of incised fumewort can send seeds springing away from the plant, so removing the plant should happen before seed capsules have formed. In parks and on other public property, do not remove the plant, but immediately report via iNaturalist as suggested above.
County staff are planning invasive removal events and need to know where to focus. Check out this project page for lots more photos: https://www.inaturalist.org/projects/invader-detectives-ncr-corydalis-incisa