Description Lobelia Fulgens Cardinalis – Cardinal Flower Marginal Plant. Dark Red Black Foliage – Brilliant Scarlet Flowers to 75cm. This very popular flower is also known as Cardinal Flower which has a profusion of large spikes of brilliant cardinal red coloured flowers held on tall stems which come from a rosette of dark red-tinged leaves.  Flowering from mid-summer to mid-autumn it adds a lovely vertical interest to the garden.  It can self-seed, but is not invasive. Plant potted in 13cm pottle.