Syn.: Narukila cordata (L.) Nieuwl., Pontederia angustifolia Pursh, Pontederia lanceolata Nutt., Pontederia lancifolia Muhl., Pontederia maculata Donn, Pontederia mucronata Raf. ex Torr., Pontederia nymphaeifolia Kunth, Pontederia obtusifolia (Raf.) A. DC., Pontederia ovalis Mart. ex Schult. et Schult. f., Sagittaria cerulea Raf., Umsema obtusifolia Raf., Unisema cordata (L.) Farw., Unisema latifolia Raf., Unisema rotundifolia Raf.
Family: Pontederiaceae Kunth
Distribution: American species – from eastern part of North America (from eastern Canada to Florida, westward to Minnesota and eastern Texas) through Central America (Belize, Costa Rica) to the south of South America (from Colombia to Brazil, Uruguay and northern Argentina). It was also introduced to southeastern Australia, South Africa and Europe (southern England, western Germany, Czechia, Switzerland and northern Italy). The genus includes 6 species, all occur in the Western Hemisphere.
Ecology: It grows in coastal areas, in pond and lake margins, in the northern part of the range from the coast to an elevation of about 500 m asl, in the southern part up to 1000 m asl. It blooms from March to November (in Florida), flowering season is shorter in colder areas.
Description: Perennial, aquatic herb, rooted in mud, with a stout, creeping rhizome. Stem 30–120 cm tall, erect, with a single cauline leaf in addition to the spathe. Leaves long-petiolate, narrowly deltate-ovate, cordate, 5–25 × 4–15 cm. Spike dense, 2–15 cm long, glandular-pubescent; flowers numerous, small, violet-blue, perianth c. 8 mm across, with a distinct tube, limb 2-lipped, with both lips 3-lobed. The fruit is a capsule.
The species is very variable, the morphological differences are most apparent in the shape of the leaves. This plant exists in a number of varieties, which are sometimes treated as full species.
Use: The Pickerelweed is grown as an ornamental plant in garden ponds.
Threat and protection: The species is listed as Threatened in Kentucky.
Note: The generic name refers to the Italian physician and botanist Giulio Pontedera (1688–1757).
These images were taken in culture, Czechia (by Ladislav Kovář, July 10, 2012), and USA, Louisiana, Jean Lafitte National Park (by Karel Bergmann, May 2014).
