Winter Pondweed

29 November 2024

Frost has blackened the garden into a new identity.

Grasses own the day, arching over the shrivelled Asters and spent Geum. As perennials sink into mush to meet the soil, the shallow ponds rise and duckweed stretches up to greet the sun.  It is a bright, verdant green, this bottle-brush forest that towers over the thin ice. Water droplets glint in the winter light; they are so evenly spaced they could have been sewn by an embroiderer’s hand.

Like the raised nap of a living fabric, this weed reminds me of ancient ballgowns, an aquatic Scheele’s green. Once popular with the fashionable ladies of Europe, the secret ingredient of the Scheele pigment was arsenic. It murdered its way through the eighteenth and nineteenth centuries before its deadly effects were discovered. A single woman attending a ball in a Scheele gown could have taken out half the dance floor, so it was said, spinning and whirling, dusting the crowd with tiny, toxic flecks.

Looking down at the duckweed, I feel uneasy. In previous years, it disappeared into almost nothing. Only a few straggling strands remained after the cycles of ice and thaw had worked their way through the cold months. This year, however, even in late November, the weed is as thick, robust, and chlorophyll-packed as it was any day in summer. Elodea densa is non-native. It’s a South American species that should have stayed in an aquarium. Given to me as a gift years ago when the newt pond was struggling to host oxygenators, only now do I learn that it is considered invasive.

The Common duckweed, (Lemna minor), is also doing well. Beloved of frogs who wear the little dot leaves as cooling caps on hot days, I am less concerned. Although its mat-forming capacity can be just as damaging, excluding light from other species and absorbing all the nutrients, somehow I feel its presence is more benign.

I should rake them both out. Dump them on the pond sides to rot down with the other vegetal matter decaying into the brown earth. Yet I would miss their bright green sheen that almost glows on dull days - they are evidence that life goes on, even in the cold dark of midwinter. Tomorrow, I tell myself regretfully. Tomorrow I will rid the ponds of this alien carpet and its equally rigorous native friend. Tomorrow.