I have had it in my garden for 30 years. I didn't plant it. I planned on removing all of it and replacing it with the native Celandine. So far, I haven't done that for one reason or another. For one thing it keeps coming back. It reseeds a lot and I have been deadheading it for the past two years. Then I decided it wasn't such a bad weed. It puts on very rapid foliage early in the season when you are dying to see anything green. It fills in around shrubs, bases of trees, along the fence. Very easy to pull when in the wrong place. Doesn't seem to mind lack of sun, moisture. Has no insect or foliar disease problems. Adds to the floral display. Best of all, when it is finished blooming and other perennials are coming into their own, they pull out very easily and are great in the compost pile.

I would rather have the native on principal. I also prefer the look of the native just a bit. I am still working toward making that change, but I don't see it happening quickly and it is not a high priority for me.

I've never heard that it is harmful to spring ephemeral plants. I've never seen it harm anything in the garden.

I think I have this in a couple of places in my garden (I'm getting the weeder immediately), and I think this is the plant my neighbor identified as leopard's bane, that we discussed on the groundcover thread.

From the PCA Alien Plant working group (the photos are pretty startling):

Ranunculus ficaria L. aka Lesser Celanine

ECOLOGICAL THREAT
Lesser celandine is an exotic spring ephemeral and a vigorous growing groundcover that forms large, dense patches on the forest floor, displacing and preventing native plants from co-occurring. The ecological impact of lesser celandine is primarily on the native spring-flowering plant community and the various wildlife species associated with them.

Spring ephemerals complete the reproductive part of their life cycle and most of their above-ground development before woody plants leaf out and shade the forest floor. Native spring ephemerals include bloodroot, common and cut-leaved toothwort, Dutchman's breeches, harbinger-of-spring, squirrel-corn, trout lily, Virginia bluebells, and many others. Because lesser celandine emerges well in advance of the native species, it can establish and overtake areas rapidly.

Here is a link that might be useful: lesser celandine

It has made a beautiful mass of yellow along the distant top of our hillside. I was thinking of using hired-man time to pull it.
HOwever keeping bees has changed my perspective on weeds. There is less and less forage for bees. At this time of year, weed flowers (like the flowers we call not-weeds) are necessary for our pollinators.

After spending an hour killing dandelions I've decided to let some areas just be what they are. Bees need them and we need pollinators for our gardens to be lush and flowerful.

Massachusetts is mounting a great effort to eradicate purple loosestrife. This is necessary. HOwever, in late summer it is the most important plant for bee forage. Even our best intentioned efforts have unforeseen outcomes.

Perhaps you'll consider letting a corner of your property go to weeds!

Marie

Well, I was thinking of a different plant. I have Stylophorum lasiocarpum, I believe, which is a yellow wood poppy only the one from China. The one I want to replace mine with is Stylophorum diphyllum which is a native.