The plant you have is commonly called Lesser Celandine and the botanical name is Ranunculus ficaria. It has been sold for years as Marsh Marigold (Caltha palustris) which it is NOT!! It has been placed on the Invasive Plant List of most states and is a tough plant to get rid of. My recommendation is to spray the plant as soon as it emerges (and usually before anything has, making this job easier) with Roundup at the recommended strength. The roots of this plant are like minature dalhias and each piece you break off makes a new plant so trying to dig it out only makes matters worse. They also spread rapidly via seed. Hope this helps some. Regards, Mark

Excellent! Thank you! Our neighbor LOVES it and has so much of it growing in their back yard. Guess we are going to have to find a "border" of some sort to prevent the spread.

Mark--what is the source of your information? I thought this was marsh marigold. I would appreciate more information.

Here is a link that might be useful: follow me on twitter

My source is years of experience dealing with this plant after it was sold as Marsh Marigold and now trying to remove it from an 11 ac. Botanical Garden. I'll do some research and send you some useful links the first of next week which should clear up the confusion regarding this plant. You are not alone in thinking this plant is something it is not. A lot of very experienced gardeners and experts still have the same misconception but hopefully it will be cleared up soon and folks will stop selling and giving it away(trading)it as such. Till then. Mark

That's disturbing that nurseries would sell a non-native plant under the same common name as a U.S. native plant. Yet another good reason to shop at places that list the botanical names of plants on the tags.

Seems like the easiest way to tell them apart is Marsh Marigold (Caltha palustris) has five petals in the flowers. The Ranunculus ficaria plant pictured above seems to have eight or maybe even nine petals in the flowers.

See link below for photos of the real Marsh Marigold.

Here is a link that might be useful: Caltha palustris/Marsh Marigold

I've seen this for sale at local gardening shows, they make it sound really great. There is also a form with burgundy leaves, 'Brazen Hussy' from Plant Delights nursery.

The really bad weed in my yard and neighboring hay fields is perhaps Ranunculus acris, tall buttercup. It has a more incised leaf. It really spreads and is very hard to eradicate.

An easy way to spot Ranunculus ficaria in it's beastly way of invasion is along stream banks. Think...if it's ALL OVER THE PLACE, that's it.

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It has covered the entire flood plain of our local creek. Even jumping to the other side of the road now. Walking through it, while battling through Rugosa rose as well, is a horrible experience.