1. Utricularia gibba L. (humped bladderwort, swollen-spurred bladderwort)

Pl. 444 i–k; Map 2013

Plants annual or more commonly perennial. Stems generally less than 20 cm long. Leaves regularly present, mostly 5–20 mm long, sessile, dichotomously divided into 2–4(–8) segments, the segments slender, not or only slightly flattened (more or less circular in cross-section), mostly tapered to minute, bristlelike tips. Inflorescences with 1–3(–4) flowers, the stalk relatively slender, glabrous. Bracts 0.8–1.2 mm long, oblong to broadly ovate, attached at the base, which partially encircles the axis, rounded to more or less truncate at the tip. Calyx lobes 1–3 mm long, broadly ovate to nearly circular, broadly rounded at the tip. Corollas (including the spur) 5–12 mm long, yellow, sometimes with reddish brown veins, the 2 lobes about the same size or the lower lip slightly smaller; the upper lip broadly ovate to nearly circular, entire or slightly 3-lobed; the lower lip broadly oblong to nearly circular, entire, the palate densely hairy, the spur 3–5(–7) mm long, shorter than to longer than the lower lip, conic to conic-cylindric, bluntly pointed (rarely minutely notched) at the tip. Fruits 2–3 mm long, globose. Seeds 0.8–1.0 mm in diameter, circular or irregularly angled in outline, strongly flattened, the rim broadly winged, the body smooth to finely warty. 2n=28. May–September.

Scattered, mostly south of the Missouri River, most commonly in the Ozark Division (eastern U.S. west to Minnesota and Texas; also Washington to California; Canada, Mexico, Central America, South America, Caribbean Islands, Europe, Asia, Africa, New Zealand, Australia). Submerged aquatic (with emergent inflorescences) in ponds, sinkhole ponds, lakes, and sloughs; also ditches; rarely stranded on mud.