Pretty, isn’t it? The problem is that the flower in the picture is Lesser Celandine (Ficaria verna), a dreaded invasive. Individually or in small numbers they are beautiful harbingers of spring. Collectively, they are a problem. Lesser Celandine is originally native to central Europe and North Africa, but has spread to other parts of Europe. It was said to be the favorite flower of the poet Wordsworth and was intended to be engraved on his tomb, but the stone cutter made a mistake and engraved the wrong flower. Because of its attractiveness, it was introduced to the United States as a garden plant in the late 1800’s and ultimately spread throughout the eastern US, Midwest, and Pacific Northwest. It is a perennial which blooms in March/April in this area (depending on weather) and is gone by June when it becomes dormant until the next year. Although it can spread by seed, it mainly spreads by sending out tuberous roots or by creating bulbils which are vegetative parts of the plant which propagate like cuttings. Bulbils can be spread by animals rooting or digging in the affected areas. Lesser Celandine is moisture-loving and tends to grow best in low wet areas. The flood plains of creeks (such as Pennypack Creek) are the prime habitat, but it may grow less profusely on uplands as well.
This picture (from http://nyis.info/invasive_species/lesser-celandine/, photo: Les Merhoff, DiscoverLife.org) shows what can happen when Lesser Celandine spreads unchecked on a forest floor.
Because of its tendency to form huge mats, Lesser Celandine can completely displace other native wildflowers from their original habitat. Once the leaves die back in early summer, large bare patches of soil are left which may be colonized by other invasive plants.
During the 15 years or so that I have been visiting the Pennypack Preserve I have noticed the gradual spread of the Lesser Celandine. When I first moved here, I would see it mostly along the banks at the south end of the preserve, but it has gradually spread north up the creek. When I was out photographing last week I passed a spot where I had photographed wild phlox next to a rotting log on more than one occasion several years ago. The log is now mostly gone, and there is just a dense patch of Celandine. The picture below was taken along the Management Trail. There is typically a profusion of grass and native Spring Beauty in April, but the lower, wetter portions of the trail are lined with Lesser Celandine.
The problem is that there is no obvious way to control Lesser Celandine. Small patches can be removed by digging them out, but this is not practical for large patches, and disturbing the patches actually facilitates their spread. Major herbicides (i.e. RoundUp/glyphosate) will kill them, but may be toxic and will kill all the native plants anyway. In the end, as is so often the case with other non-natives, we may have to learn to live with them. They are not without beauty, and are beloved by English authors. In “The Lion, the Witch, and the Wardrobe,” C.S. Lewis refers to Lesser Celandine carpeting the forest when Narnia is released from winter. J.R.R. Tolkien refers to Celandine in the Lord of the Rings. And, of course, Wordsworth wrote an ode to Celandine. When I look at my picture at the top of this post, I still see a pretty flower. If I knew of a way to control it safely, I would be in favor of it, but if not, I may have to learn to love it a little.