About 15 years ago I admired pretty little plants with yellow flowers growing in a friend’s lawn, and with her permission, dug some up and planted them in my newly established mini-forest. I thought they were the native marsh marigold, Caltha palustris. My site is much drier than hers, so it took a few years for them to really take hold, but now they cover perhaps 20 square feet of my forest area, and the clumps expand every year. You’ve probably realized by now that I didn’t plant marsh marigolds. Instead, I mistakenly planted lesser celandine (Ranunculus ficaria), an invasive plant that’s extremely widespread in wet, shady areas throughout the Northeast.
Lesser celandine is almost impossible to dig up, because thousands of tiny bulblets are attached to the roots, the root system is very fine, and if you leave any bulblets the plants regrow vigorously. So this year I decided to try to smother it. As I clear my perennial beds, I’m dumping big piles of leaves on top of it. So far I’ve found that a six-inch layer of leaves isn’t enough: the plants grow right through. So I keep dumping more; probably at least some of it will die this year. And I’ll most likely weaken what remains. Right after the picture was taken, I buried the remaining clumps under about 18″ of leaf litter.
You may wonder why a plant like this is a problem. It’s pretty, it attracts pollinators, and it doesn’t strangle or otherwise hurt the native woody plants growing all around it. All true, but it crowds out natives. The forest floor used to be lovely with violets in spring and common lobelia in summer; now both are gone.
Some invasives can be difficult to distinguish from native plants. Look at this guide if you’re in doubt.
Happy Earth Day! We all make mistakes in the way we treat the earth, but we can all at least try to correct them.