With its sometimes-swampy landscape stippled with soaring cypresses, Congaree National Park in central South Carolina looks like a prehistoric diorama. And occasionally it also resembles a Lisa Frank folder come to life. When conditions are right, standing water appears orangey, blue, and pinky-red—hues usually reserved for garish school supplies or swirls of melted sherbert on a hot day. The sheen comes from oil, but isn’t the product of a spill or other industrial mess-up. Rather, the “oil-slick sheen” comes from Taxodium—the genus of water-loving conifers in the cypress family—which produce…
