Habit: Aquatics growing in or on water, Aquatic submerged, Aquatic leaves floating, Aquatic marine, Herbaceous, Perennials

Roots: Rhizomes, Sap clear

Stems: elongate, solid

Leaves: Leaves - sheathing at base, Leaves - sheath open, Leaves - sheath closed, Leaves - simple, Leaves - cauline, Leaves - alternate, Leaves - 2-ranked (distichous), Leaves - linear or filiform (grass-like), Leaves - venetion parallel, Leaves - ligulate, Leaves - soft, Leaves - margins entire

Inflorescence: lateral or axillary, bracteate, spikes, fleshy spadix, subtended by large spathe (leaf-like bract), Flowers sessile

Flowers: Flowers unisexual, Plants dioecious, Plants monoecious, Perianth present, Perianth reduced to bristles or scales, Perianth absent, Flowers minute barely visible, Flowers small, Flowers 2 merous, Flowers zygomorphic, Floral bracteoles present

Stamens: Stamens 1, Stamens 2

Pistil: Carpels separate (apocarpous), Carpels united, Carpels 2, Ovary superior, Styles 1, Stigma terminal capitate or trilobed, Locules 1, Placentation basal (or apical)

Fruit: Fruit - achene (nutlet), Fruit - drupe, Fruit 1-seeded

Seeds: Seeds - single per locule, Seeds - lacking tuft of hair