Heteranthera rotundifolia (Kunth) Griseb.
CC = 5
CW = -5
MOC = 29
Family - Pontederiaceae
Stems - Creeping, with well-separated nodes.
Leaf - Dimorphic. Seedling leaves linear. Main season leaves long-petiolate. Blades to 5 cm long, mostly longer than wide, lanceolate to ovate, cordate at base, tips rounded, glabrous.
Inflorescence - Flowers borne singly on specialized flowering stems to 12 cm long.
Flower - Perianth of 6 tepals, zygomorphic, purple to white. Tube to 29 mm long, lobes to 18 mm long. 3 tepals erect, 2 spreading, 1 pendent. Central upper tepal with yellow base. Stamens 3, unequal, with glandular-hairy filaments.
Flowering - July - October.
Habitat - Open mud, shallow water.
Origin - Native to the U.S.
Other info. - This is one of the larger-flowered members of the genus found in Missouri. It can be identified by its strongly zygomorphic perianths, having three of the tepals erect. The flowers are quite attractive up close.
Photographs taken at Otter Slough Conservation Area, Stoddard County, MO, 8-13-2015 (SRTurner).