2. Heteranthera limosa (Sw.) Willd. (mud plantain)

Pl. 189 a–d; Map 765

Plants annual. Vegetative stems short except in deeper water, not creeping. Leaves dimorphic, clustered, the rosette leaves of seedlings linear and lacking a well‑defined blade, the emergent, later leaves long‑petiolate, the blades 1–5 cm long, oblong to ovate, truncate to acutely angled at base, the tips mostly acute. Inflorescences produced on specialized flowering stems, these 2–24 cm long, erect to spreading. Flowers single, sessile at the tips of the flowering stems. Perianth purple to white, zygomorphic, slightly 2‑lipped, the tube 15–45 mm long, the lobes linear, 5–16 mm long, the middle lower lobe slightly longer than the others, the 3 upper lobes with yellow spots at their bases. Stamens nearly the same length, the filaments glandular‑hairy. 2n=30. June–October.

Scattered in the southern half of the state and along the Missouri River (U.S., mostly in the central and western states, south to South America, West Indies). Emergent aquatic, usually in shallow, stagnant or slow‑moving water or along muddy margins, in ponds, lakes, ditches, sloughs, and rice fields.