Perennial herb to 1 m tall. Leaves erect, the stalks to over 20 cm long. Leaves mostly ovate, cordate, to 20 cm wide. Flowers each about 1 cm wide, hairless, arranged in a spike, blue or sometimes white; summer. This is the cultivated form.

Eastern North America to the Caribbean

var. lancifolia (Muhl.) Torr. Leaves lanceolate. Flowers glandular hairy, spike longer than in the type. This variety has become naturalised. [P. lanceolata Nutt.] Naturalised in WA, Qld, NSW and Vic.

Source: Spencer, R. (2005). Pontederiaceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 5. Flowering plants. Monocotyledons. The identification of garden and cultivated plants. University of New South Wales Press.