NC Plant Conservation & Beyond: Spring Scourge: Lesser Celandine (Ficaria verna)

Lesser Celandine in Richmond, VA (3/18/2018)

This Euroasian member of the Buttercup family (Ranunculaceae) has been introduced in North America since at least the 1860's. It hid under the radar in North Carolina until ~ 2005 (see Krings, Weakley, Neal, and Swab. 2005. SIDA, Contributions to Botany 21(4):2429- 2437), but has now spread to at least 7 counties and likely more.

The distribution in Virginia is shown to the right; from the Digital Atlas of the Virginia Flora. (http://vaplantatlas.org)

The plant is becoming all to familiar to many of us. According to Meghan Fellows, speaking about the Washington D.C. area, "Yes, it is getting worse. Floods and dispersal events spread this plant throughout our area. They are also extremely good at taking over new ground. Those pesky yellow carpets of weeds have replaced what should be a bounty of spring ephemerals (and their pollinators)." (https://www.lfwa.org/updates/tips-controlling-lesser-celandine).

According to USDA APHIS, the species is now naturalized in 26 eastern states, as well as Oregon, Washington, and several provinces in Canada (See citation below). Calling large infestations "pesky yellow carpets" is an apt description that certainly applies to areas in and around Richmond, Virginia where I have seen the species (pictured below).

Carpet of Lesser Celandine in floodplain forest, Richmond, VA (04/10/2018)

There is some evidence these carpets are inevitable, once the plant becomes established. They emerge on the forest floor in the late winter before other species leaf out and produce above-ground bulbils which greatly aid in dispersal (Verheyen & Hermy 2004. J. Veg Sci 15:125-134)

Plants also develop extensive tubers that easily break off with mechanical disturbance and tend to survive many above ground treatment methods.

According to M. Fellows (cited above) the spreading carpets "are painful to watch - we want to DO something. Unfortunately, science has not kept up with our need. There is NO good, reliable way to kill celandine" (emphasis added).

There is a relatively short window between the plant's emergence and senescence when control is possible. While I am convinced that control is possible, given enough dedication and commitment, thus far, I have not shown enough of either. I have found little evidence of anyone else who has either, but am heartened and surprised by the efforts of some seemingly unlikely groups such as the Cleveland, Ohio Metroparks (see their herculean job described here): https://bugwoodcloud.org/mura/mipn/assets/File/Educational%20Resources/Lesser%20Celandine%20Control%20Program.pdf

For conspiracy theorists, I ran across this fascinating bit on the web: "And please dear listeners and readers, don't go around trying to wipe this plant out everywhere you see it because it's on some hit list. It's not going to go away-and that "hit list" may well have been instigated by Monsanto or some other herbicide producer. Lesser celandine stabilizes wetland area brilliantly, and the buttercup-like flowers are breathtaking in the spring" (https://www.gardensalive.com/product/lesser-celandine for-some-a-bitter-buttercup) .....WOW!

Below I illustrate examples of how this plant moves and spreads. Perhaps they start innocuously when a homeowner acquires the "breathtaking" plant from a website much like the one I just just cited. Soon the yard is engulfed and the mowing spreads the bulbils to the neighbors. From there plants wash into an adjoining drainage swale, and eventually run down-slope into the nearest creek, where overbank flooding pushes them into adjoining riparian forests. Invariably, these riparian areas are crisscrossed by sewer lines which need to be maintained by heavy equipment which disturbs the soil, spreads the tubers to the next job site......

Ficaria verna is this house's groundcover, note rosettes in the adjoining mowed lawn

Ficaria dominates this drainage swale in the same neighborhood as previous

The bright green, linear band is Ficaria downstream from previous;
the wet woods in the background (one of Richmond's premier parks/natural areas)
have already been invaded.