Aquatic herbs, usually anchored to substratum. Stem Onions) filiform, terete, ± dimorphic, green above the substratum or floating, other colourless ± buried in substratum. Leaves polymorphic, with 1-3 primary segments, those above the substratum palmately dissected, with glabrous, entire, flattened segments with few or no bladders; those beneath the substratum much reduced with bladders. Bladders ovoid, stalked, 0.8-2.0 mm long, arranged lateraly on segments, with much branched antennae. Inflorescence erect, 8-18 cm long; peduncle filiform, terete, glabrous. Scales 2-3, ovate, 1.4-2.0 mm long, basifixed. Bracts basifixed, broadly ovate, base auriculate. Flosyer 5-8, pedicel erect, deflexed in fruiting. Calyx lobes subequal, 1.8-2 x 1.4 mm, ovate. Corolla pale yellow, 6-8 x 4.5-5 mm; upper lip ovate-oblong with refuse apex; lower lip broadly obovate, with retuse apex, lateral margins curved downward. Spur short, subconical, not longer than wide; filaments curved. Stigma upper lip smaller, 2-fid, apex acute; lower lip broadly ovate, ciliate, apex reflexed. Ovary broadly ellipsoid. Capsule globose. Seeds prismatic, unwinged.