Fig Buttercup: A New Invader to Look Out For!

I See Weeds...

I must of have looked pretty odd to anyone passing by. This past Saturday I was the Lincoln Park Zoo in Chicago with my daughter. We were in front of the snow leopard pen, and this rare cat was active and just a few feet away. I had my camera out, but instead of taking a picture of the fine feline, I had my camera pointed down at the ground. I was taking a picture of this:

 

 

Most people wouldn't even notice the plants on the ground in front of the snow leopard. If they did, they would probably have simply assumed these were violets or creeping charlie and not paid any attention. But as a botanist, I notice plants and I had seen this plant before. Its not good.

This is a large colony of fig buttercup, also called lesser celandine (Ranunculus ficaria, (formerly Ficaria verna)). In Illinois where I found this plant its listed on the New Invaders Watch Program and has recently been listed as a Noxious Weed by the State. 

In Wisconsin, it is a Prohibited invasive plant listed under the NR-40 Invasive Species Rule. This means that within Wisconsin you "cannot transport, possess, transfer or introduce" this species and that "Control is required." Wherever it is found.

There are only a few reported populations of fig buttercup in Wisconsin at the moment and its the DNR's intention to keep it that way. There are two populations near Lake Geneva. Two in the Milwaukee area. And we here at Good Oak know of two in the Madison area. One we treated at Eagle Heights on the west side of the UW campus last year (which had started to spread into the woodland at the Lakeshore Preserve!). And this Tuesday we discovered a new population, at a condominium complex near Old Middleton and Old Sauk Road on Madison's west side.

Report Fig Buttercup if you find it!

The DNR needs our help finding and eliminating any populations. If you do find this species, report it by emailing invasive.species@wi.gov.


So far we've been finding them in semi-shady sites, where perennials have been planted at some point. I suspect its being moved around as people share plants. At the Eagle Heights site it looks like it may have spread into the lawn from an abandoned edge bed. At the condominium complex, it was mixed among many "ornamental" ground covers, plants that I consider invasive like vinca (periwinkle" pachysandra, Lamium (purple deadnettle). In particular it was well mixed in with one patch of pachysandra, so I suspect it was dug from another site and accidentally moved with the pachysandra, but it has spread throughout the area, so it may have been moved there intentionally on its own.

Identification: 

Here are some photos I've taken of this species to help with identification. It looks a lot like early buttercup or small-flowered buttercup (which will be individual plants, not forming colonies, and only 5 petals on the flower), or marsh marigolds (which only grows in wetlands), or even common violets (which have entirely different flowers and pointed tips on the leaves). I've also noticed some variegation (lighter patches) on the leaf surfaces. Its leaves are never more than 6" tall, it has multi-petaled yellow flowers that bloom in mid-spring. Control is most effective before it flowers.

This is what it looks like early in the season, late-March 2016.

This photo was taken late in the blooming period, late-April.

This flower was getting a bit old, so the petals are more spread out and the white patches are where it has faded a little.

UPDATE: I've created a Weed Identification and Control Sheet for Fig Buttercup. Take a look, and share!

In the mean time, you can find more information at these sites:

http://dnr.wi.gov/topic/invasives/fact/lessercelandine.html
http://www.nps.gov/plants/alien/pubs/midatlantic/five.htm
http://www.newinvaders.org/species/fig%20buttercup.pdf

Control Methods:

A spot herbicide application of glyphosate (Round-Up®, etc.) at 1.5% active ingredient appears to be the most effective chemical control method, and glyphosate breaks down fairly quickly in the environment, so its relatively safe to use. However, if you want to try to avoid killing neighboring grasses, you can try triclopyr (Garlon® 3A, etc.) This is proving to be less effective, so multiple treatments will be needed. Spraying early in the season, late-March or early-April, well before the plant flowers, appears to be the best timing for maximum control.

Digging may not be particularly effective since the roots are a series of bulb-like structures that would break apart pretty easily, leaving some behind. So, dig carefully and be thorough. You'll need to destroy the plants you dig in fire, or double-bag the entire root and soil mass in sturdy trash bags and put it into the trash.

Remember to report your population the the WI DNR, and carefully monitor the area for several years after treatment and eliminate any survivors.