Herbs perennial, submersed, hydrophilous, monoecious. Roots absent. Stems glabrous, branched, free or attached by slender shoots. Stipules absent. Leaves cauline, 3--11 in a whorl; petiole inconspicuous; leaf blade divided dichotomously into filiform segments; segments with 2 rows of denticles. Inflorescences reduced, solitary or with vestigial branches, 1-several at a node, extra-axillary, alternating with leaves, sessile or peduncles lengthening in fruit; involucre of 8--15 foliaceous bracts; bracts 1.5--2 mm, apex terminated by 2 denticles and a medial multicellular appendage. Flowers naked, subsessile. Staminate flower: stamens 3--50, spiral; filaments short; anthers 2-celled, dehiscing by longitudinal slits. Pistillate flower: pistil 1, simple; ovary 1-loculed, placentation laminar; ovule 1, pendulous; style persistent, short or elongate; stigma decurrent. Achene leathery, indehiscent, ellipsoid, smooth or tuberculate, basal spines 0--2, facial spines 0--2, marginal wing present or absent, marginal spines 1--8. Seed 1, unitegmic, endosperm and perisperm absent; cotyledons fleshy.

Kuan Ke-chien. 1979. Ceratophyllaceae. Fl. Reipubl. Popularis Sin. 27: 15--19.

One genus and six species: cosmopolitan; three species in China.

(Authors: Fu Dezhi; Donald H. Les)