Heteranthera limosa (Sw.) Willd.
CC = 5
CW = -5
MOC = 33
Family - Pontederiaceae
Habit - Annual forb.
Stems - Short, not creeping.
Leaves - Seedling leaves linear. Later emergent leaves long-petiolate. Blades to 5 cm, oblong to ovate, acute or truncate at base, glabrous.
Inflorescence - Flowers borne singly from sheathing spathe on specialized flowering stems.
Flowers - Perianth zygomorphic, purple to white, with elongate tube to 45 mm, lobes to 16 mm. Perianth usually with 3 ascending lobes, 2 spreading lobes, 1 pendent lobe. Upper lobes with yellow spots at base. Stamens 3, subequal, with glandular-hairy filaments. Ovary 1, with 3 locules. Style 1.
Fruits - Slender, thin-walled capsules to 2 cm long. Seeds numerous, 0.5-1.5 mm long, with 8-22 longitudinal ribs.
Flowering - June - October.
Habitat - Mud flats or shallow water.
Lookalikes - Other members of the Heteranthera genus, especially H. rotundifolia.
Origin - Native to the U.S.
Other info. - This pretty species is found scattered across much of the state, in open areas of mud or shallow water. It can look similar to other members of the genus, and is most readily distinguished by having leaves with truncate bases (not cordate), flowers borne singly from the spathe, and long (4 cm) perianth tubes. The perianth color varies considerably, from very pale to dark blue.
Photographs taken at Busch Wildlife Area, St. Charles County, MO, 7-18-2013; Otter Slough Conservation Area, Stoddard County, MO, 8-13-2015; and near the Augusta Katy trailhead, St. Charles County, MO, 8-3-2015 and 9-29-2019 (SRTurner).