‘Purple Flame’ Blue Flag Iris blooms in late spring, putting out dark blue flowers over unusual foliage which starts the season with vivid purple coloration. The blade-like leaves transition to green as the weather warms up, but the combination of purple foliage and dark blue flowers in spring is really unique. Iris versicolor ‘Purple Flame’ is a chance mutation found by a gardener at the Mt Cuba Center. All Iris versicolor will grow beside or in water, so this is a great addition to stream and pond edges.