Cardinal Flower, Black Truffle Cardinal FlowerBlack Truffle Cardinal Flower is an upright native herbaceous perennial with glossy near black foliage that fades to dark maroon and green when the flowers emerge. Erect stalks of vibrant cardinal red tubular flowers bloom late in summer. Prefers afternoon shade and moist to wet well drained soil. Foliage is highly toxic if ingested. Lobelia cardinalis acts a sa native host for several species of butterflies, and the nectar as a food source for