CERATOPHYLLACEAE, Hornwort Family
Submersed aquatics; stems elongate, branched; leaves whorled, sessile, dichotomously dissected into filiform, often toothed, divisions; monoecious; flowers minute, hypogynous, monosporangiate, solitary in axils; calyx (or calyxlike involucre) cut into s..14 divisions; corolla none; stamens 10-20; carpel I, style slender; ovule I; fruit indehiscent.
Ceratophyllaceae