Aquatic herb. Stolons filiform, up to 50 cm. long or more, flexuous, ± densely villous; internodes 1–10 cm.; rhizoids absent. Leaves with 1 or 2 primary segments 1.5–4 cm. long, ovate in outline, pinnately divided; rhachis filiform throughout or ± inflated, especially in the lower half, villous; pinnae alternate, the lowermost up to 1.5 mm. from the base of the rhachis, repeatedly dichotomously forked, ultimate segments capillary, sparsely setulose. Floats terminal on short lateral slightly inflated villous branches, verticillate, 4(–5–6)–9, fusiform or narrowly cylindrical to ovoid or ellipsoid, 0.3–2.5 cm. long, bearing in the distal half a number of leaf-segments. Traps usually not numerous and often absent from some leaves, inserted in the angles between the leaf-rhachis and pinnae and between subsequent dichotomies of the leaves, ovoid, long-stalked, villous, 1–3 mm. long; mouth lateral; upper lip with 2 simple or ± branched hairs; lower lip naked or with 1 or more shorter simple hairs. Inflorescence erect, 3–25 cm. high, terminal on the short stolon-branches, arising from the centre of the whorl of floats; flowers 2–10, the uppermost congested, those below ± distant; cleistogamous flowers often present at the scape-base among the floats; scape filiform, straight or flexuous, smooth and glabrous; scales absent; bracts basifixed, deltoid or ovate, ±1.5 mm. long; bracteoles absent; pedicels capillary, erect, 2–3 mm. long at anthesis, up to 10 mm. long in fruit. Calyx-lobes subequal, orbicular, membranous, ± 1 mm. long at anthesis, scarcely accrescent. Corolla mauve or pale purple with a yellow blotch on the palate or wholly white, 10–15 mm. long; upper lip oblong, 3–4 times as long as the upper calyx-lobe, ± auriculate at the base, deeply divided into 2 parallel lobes; lower lip reniform, 7–10 mm. wide, apex ± emarginate; palate with a narrow raised ± crenulate rim; spur cylindrical or botuliform, 2–3 times as long as the lower lip, 8–10 mm. long, 2.5–3.5 mm. thick; corolla of cleistogamous flowers obsolete or nearly so. Filaments filiform; anther-thecae confluent. Ovary ovoid; ovules 3–20; style short but distinct; stigma lower lip ± quadrate, upper minute, deltoid or ± obsolete. Capsule ellipsoid, 2.5–3.5 mm. long, circumscissile. Seeds few, sometimes only 2, lenticular with a narrow irregular wing, ± 1 mm. in total diameter; testa-cells indistinct, elongated.
