Lesser Celandine vs Marsh Marigold: Which Is It?

Count the yellow parts, then look at the leaf edge. Lesser celandine usually has eight petals and a smooth, glossy leaf. Marsh marigold has five to nine petal-like sepals and a scalloped leaf edge. One is an invasive groundcover that should come out. The other is a native wetland plant that should stay.

The count test

Pick one open flower. On lesser celandine, count eight yellow petals; Wisconsin DNR says some plants have up to 12. On marsh marigold, count five to nine yellow, petal-like sepals. The sepals are shiny and waxy.

Then check the leaf. Lesser celandine leaves are smooth-edged, dark green and glossy, and up to about 2 inches long. Marsh marigold leaves are scalloped or toothed, up to about 4 inches long and wide, and sit on long stalks.

The root test that decides it

Lesser celandine produces two kinds of storage organs: underground tubers and small above-ground bulbils where the leaves join the stem. Marsh marigold produces neither. That difference matters because the bulbils are why digging often fails. They detach as the plant dies back and start new plants.

If you cannot see the roots, do not dig to find out. Come back in early spring when the flowers are open, or send photographs to your local extension office.

Leave it or remove it

The answer is deliberately one-sided. Marsh marigold is a native plant, and in North Carolina it is listed as endangered on the state Protected Plant list. Protection is decided state by state, so check your own state’s natural heritage program or agriculture department before you dig anything in wet ground.

Why lesser celandine is the problem

Lesser celandine emerges earlier than most native spring plants and forms a dense carpet that shades them out. It was introduced from Europe and the Caucasus and has naturalized in 19 states. It spreads by bulbils, tubers and seed. Wisconsin DNR reports up to 70 seeds per plant, and the bulbils form after flowering. By early summer the leaves die back and the plant disappears underground until the next spring.

That short growing season is the whole control problem. NC State Extension says the plant is best targeted while it is actively growing in February and March. In Wisconsin, flowers open in March and April; NC State Extension gives March to May for its region. The window shifts with latitude, which is why a calendar date from another state is not a plan.

If it is lesser celandine

Dig only while the plant is actively growing, and only if you can remove the tubers. Once the bulbils have formed, digging disturbs them and can spread the patch. University of Maryland Extension notes that after dormancy the only mechanical option is screening bulbils and tubers out of the soil, which is not practical in a lawn or woodland bed. Expect more than one season of work.

Wisconsin DNR lists foliar glyphosate for this plant. That is an active ingredient named by the source, not a rate or a recommendation for your site. Follow the product label; the label is the law. For the full sequence, see lesser celandine removal.

For the species profile, see lesser celandine. For the other pairs, see look-alikes. For native and invasive plants by category, see plants.