Early spring is prime time to be on the lookout for the invasive plant lesser celandine along your streambanks and in your wetlands.

Lesser celandine is a low-growing green plant that flowers in March and April. Its heart-shaped leaves are dark green and shiny and grow on short stalks. The Latin name for this plant is Ranunculus ficaria.

Lesser celandine

Be on the lookout for lesser celandine, a wetland invader.

Lesser celandine has bright butter-yellow, daisy-like glossy flowers. These flowers usually have 8 “petals” (they are technically sepals, according to botanists) that emerge from a central disk. One plant can have many flowers but each flower grows on its own stalk.

This invasive weed reproduces rapidly by seed and also through white-ish “bulblets” that grow where the stems come together after the plant is done flowering for the year. Lesser celandine also has below-ground tubers that are thick and finger-like. Both the bulblets and tubers are storage organs that help keep the plant alive through summer and fall when the leaves and stems have died off after flowering.

One high-quality native plant that folks sometimes confuse for lesser celandine is marsh marigold (its Latin name is Caltha palustris).

Marsh marigold

Don’t confuse this native wetland plant, marsh marigold, for the invasive lesser celandine.

Marsh marigold also has shiny dark green, heart-shaped leaves and also blooms in the spring, but it grows in different habitat and has fewer petals. You’re most likely to find marsh marigold blooming singly or in small groups around a wetland or in a stream or lakeshore setting where there is water or saturated mud. You won’t find it higher up on the bank on drier soils. Its flower parts are also different: marsh marigold flowers have 5-9 yellow petals, whereas lesser celandine’s flowers have 8 or more petals. Marsh marigold also doesn’t have tubers or bulblets.

Lesser celandine has only recently invaded Wisconsin, which makes its control all the more important now, before it spreads and gets out of control.

If you find a plant that you think is lesser celandine, take photos of the plant and/or collect a sample, note the location of the plant, and contact your local WDNR Aquatic Invasive Species coordinator or Kelly Kearns.

Find more information about this wetland invasive species (including how to control it) on the WDNR’s website.

Photos by Leslie J. Mehrhoff (University of Connecticut, Bugwood.org), Brian Russart, and Kate Redmond.