As the sun rose on a residential street in Denver’s West Washington Park neighborhood, the loudest sound along the sidewalk was the chirping of insects hidden among gardens of native plants. Avi Stopper, thermos in hand, surveyed his front yard. A magenta desert willow bloomed, and a small bee crawled on an aromatic aster, a bush bearing purple flowers. Stopper walked to the sidewalk to point out chocolate flowers — yellow wildflowers named not for their color, but for their fragrance. All around him, native plants were thriving.