Q: I have an infestation of (see picture) in numerous parts of my lawn. It seems resistant to lawn weed killer. Any suggestions?
A: The plant in your photo is a pretty little native wildflower known as the lesser celandine or pilewort (for its medicinal properties), or to give it its proper Latin name, Ficaria verna ssp verna. Its species name, ‘verna’, means “spring blooming”, and is a clue to the fact that this vigorous, quick-spreading hardy tuberous perennial is one of the very first native wildflowers to appear after winter with a long blooming period that stretches from February to May.
If given the kind of growing conditions that it loves (a cool, moist soil in light shade), lesser celandine can form a dense carpet of growth and quickly colonise large stretches of ground including, as you’ve discovered, lawns and flowerbeds. For this reason, many gardeners consider it to be an invasive weed, especially as it’s so vigorous that its dense rosettes of heart-shaped leaves can stifle the growth of smaller garden plants. A native of many European countries, its cultivation is outlawed in several US states where it’s classed as an invasive alien species.
On the plus side, its jolly, yellow starry flowers are a great source of nectar and pollen for early emerging pollinating insects, while the plant starts to naturally die back in early summer as it enters a six-month-long period of dormancy, meaning it’s not a problem for the latter half of the year. Less invasive cultivated forms with interesting coloured flowers or foliage have also been intermittently popular with gardeners over the years, including the jauntily named ‘Brazen Hussy’.
A distinctively dark-leaved variety, the late, great British gardener Christopher Lloyd helped to make it fashionable after he discovered it growing wild in the woodlands near his home and garden at Great Dixter. (I wonder if someone would get away with bestowing that particular name upon a plant these days).
A member of the buttercup family, attempts at eradicating it from your garden are almost certainly doomed to end in failure, as lesser celandine is an impressively resilient plant that’s resistant to most herbicides. It overwinters by means of its many tiny fleshy tubercles and underground tubers (like miniature potatoes), each one of which has the potential to grow into a new plant if left in the soil. But regularly mowing your lawn will certainly do a lot to keep it under control.