There's no explaining them, save sunlight, soil and abject vacancy. In downest downtown St. Louis, just up the gravel road from the corner of Lewis and O'Fallon, in an abandoned warehouse-and-train-track district, next to the 1964 Dickson Pumping Station and stretching all the way to the Trans Petro oil tanks on the banks of the Mississippi River: sunflowers. Fifty feet wide and a quarter-mile long they grow in mad thickets, dense as nettles, gangly as teenagers, bright and lush as greenhouse mums. If you've ridden the Riverfront Bike Trail, you've passed them but never seen them; they grow on the western side of the cement wall separating the path from the river. In the summer and early fall, you can find the sunflowers by parking at the start of the bike trail, near the old Union Electric power station, that marvel of Gothic arched windows and blackened brick just two blocks north of Laclede's Landing. You stroll up Lewis to the first power-line pylon, and to the west you see the Cotton Belt Route freight depot -- now a squatters' refuge -- to the east, only the graffitied cement of the floodwall. But all around you is a field of green and yellow. It's a tranquil walk: Queen Anne's lace grows wild here as well, monarch butterflies spiral like embers, and the gravel road curves, untraveled, nearly as clean as a country road. When industry left and buildings were razed, the sunflowers reclaimed the cracked mud and sandy riverside soil. Urban blight should always be so beautiful.