A submerged, aquatic herb floating close to the surface. Stems filiform, very slender, almost villous from extremely fine spreading hairs. Leaves heteromorphic; normal leaves from a line to more than 1 in. apart, simple or of 2–3 rays, not auricled, rays 5 to 8 lin. long, finely filiform and repeatedly divided from 1–2 1/2 lin. above the base or inflated and spindle-shaped up to the middle and multifid above, delicately villous in the lower part; ultimate segments capillary, very sparsely and minutely setulose, with or without bladders; bladders 1 or few on a pinna, obliquely globose-ovoid, 1/2 lin. in diam., mouth sublateral, oblique, oblong, delicately fimbriate; float leaves 5–6 in a whorl, lanceolate-oblong in outline, terete, attenuated into a short stalk, 4–6 lin. long, up to 1 1/2 lin. in diam., with short multifid sometimes bladder-bearing pinnæ near the apex. Racemes terminal at the end of stems bearing foliage- and float-leaves, 4–2-flowered, the uppermost 2–3 flowers rather close, the 3rd or 4th (if present) about 1 1/2 in. below them; peduncle very slender, glabrous, about 1 1/4 in. long to the lowest flower, without scales; bracts ovate, nerveless, scarcely 1/2 lin. long; bracteoles 0; pedicels filiform, 1 1/2–2 lin. long, suberect also in fruit. Sepals subequal, ovate-orbicular to depressed-orbicular, 1/2 lin. long, slightly larger in fruit. Corolla lilac with a violet mark on the palate, 4–5 lin. long; upper lip ovate, 2-lobed to the middle, 1 1/2 lin. long, lobes obtuse; lower lip reniform-orbicular, 2 1/2 lin. long, 4 lin. broad, sides turned up; palate rather flat with 2 slight papillose gibbosities; spur cylindric, obtuse, 3 1/2–4 1/2 lin. long, almost 1 1/2 lin. in diam., obtuse, slightly curved upwards. Anthers 1/4 lin. in diam.; filaments filiform, 1/2 lin. long. Style distinct, over 1/4 lin. in the fruit; upper stigmatic lip obscure; lower ovate, large. Capsule globose, 1 lin. in diam.; seeds subprismatic, more or less 4–5-angular, about 1/5 lin. in diam., 1/2 lin. high, angles narrowly winged; testa reticulate. Embryo slightly concave on the top face.
