That pesky Yellow flower…
So after our volunteer day today, I headed out to Hamorton Woods Homeowners Association to lead a invasive species/trail maintenance clinic as a portion of a Landscape Visionaries session
and I noticed my "nemesis" in early spring everywhere that I looked, so I thought I would take the time to let everyone know about that yellow flower that seems to invade the banks of the Brandywine (and every other stream, creek, and river in the tri-state area): Ranunculus ficaria (lesser celandine). This is the blog post that I shared last year and I believe it is important to share it again.
Ranunculus ficaria is a small low growing plant with a very impressive underground network of bulbets and tubers that can continue to flourish if separated from the main plant. The flower is typically bright yellow and the leaves are a deep green.
The leaf of celandine, which is the only part of the plant that is currently showing, looks VERY similar to the leaf of a violet. Note in the photograph the violet is on the left and the celandine is on the right. Violet's tend to have more rounded lobes, and the celandine is sharper with points. Typically the celandine has a glossier look than the violet. You should be sure that you can differentiate between the two before you pull out leaves that belong to violets. Once they bloom, they are easier to differentiate, but not all violets are purple or white, there are yellow violets native to our area. Also, once the blooming has begun, it is typically more difficult to remove all of the tubers from the ground.
When you pull out the celandine be sure to remove all of the tubers and bulbets that are attached to the plant. You can actually assist in the spreading of the plant by leaving them behind. I will lay the plant on a rock where it has little chance of re-sprouting in the ground. You can also control celandine by spraying a glyphosate based herbicide at a low concentration. Glyphosate is non-selective so it should be used with care since you may harm some of the spring ephemerals in the process. If the area is very sensitive, I would recommend individually painting each celandine leaf. This may be time consuming, but it is a great way to be very selective and to inhibit any further spread. Typically manual control is recommended for very small infestations and you will have to resort to chemical to obtain complete control when you are dealing with the "blanket" effect as in the earlier photograph.