English holly certainly looks festive this time of year, with its dark, spiky leaves and bright red berries. But as recently reported in High Country News, the invasive plant poses a significant threat to Pacific Northwest forests. Much like English ivy, English holly is shade-tolerant, meaning it can thrive in the dense forests of western Washington and Oregon. It forms a dense undergrowth that can overtake native species, significantly changing forest composition and reducing biological diversity.

David Stokes is a professor emeritus of ecology and conservation biology at the University of Washington Bothell. He joins us with more details about the spread of English holly in the Northwest and what’s being done to combat it.