Limnophyton Miq.

Perennial aquatic and marsh herbs. Leaves erect; leaf-blade with obtuse to rounded apex; base sagittate or cuneate; blade and petiole glabrous, scabrid or pubescent. Peduncle longer than the leaves; inflorescence of 4–7 whorls of flowers, the lowest sometimes with 2–3 branches; upper whorls of ♂ flowers, lower of hermaphrodite and ♂ flowers; bracts 3, membranous, glabrous or pubescent; bracteoles 3 or more, glabrous or pubescent, smaller than the bracts. Sepals 3, spreading. Petals 3, larger than the sepals, white. Stamens 6; filaments broadened at the base. Carpels 10–30, free, ovoid; style ventral; ovules solitary, basal; abortive carpels in the ♂ flowers 0. Achenes crowded on the small receptacle, swollen, with lateral air-chambers, ridged. A genus which is regarded by some authors as being monospecific. However, the differences between the two species described here are constant, and too diverse to be variations of the same species. A third species, L. fluitans Graebn., with linear-lanceolate leaves and small (3 × 2 mm.) achenes which are sharply ridged and shiny when dried, has been found in the French Cameroons and S. Nigeria. This appears to be very rare, and has not so far been discovered in our area.