Alismataceae

Diagnosis: Aquatic herbs. Leaves with sagittate laminas on elongate petioles arising from a basal rosette. Inflorescence a paniculate scape rising above the leaves. Flower petals 3, free, white; gynoecium apocarpous consisting of numerous simple pistils. Fruits achenes aggregated in globose heads originating from the apocarpous gynoecium.

Habit: Aquatic herb to ca. 30 cm tall.

Main axis: Stem reduced, basal, or subterranean.

Leaves: Leaves simple, basal; petioles to ca. 20 cm long; lamina sagittate, to 4 x 12 cm, the base sagittate, the apex acute-rounded, the margins entire, the secondary veins parallel from the base, the tertiary veins conspicuously perpendicular to secondary veins.

Inflorescence: Inflorescence a racemose scape to ca. 60 cm tall emerging from within the petioles of the basal leaves.

Flowers: Flowers short-pedicillate, arranged in whorls of two or three at regular intervals along inflorescence axis; calyx actinomorphic, sepals 3, green; corolla actinomorphic, the petals 3, free, white to cream, ephemeral; stamens six; gynoecium apocarpous of few to many simple pistils.

Fruit: Fruit achenes aggregated in globose heads originating from the apocarpous gynoecium, tiny, brown when mature.

Seeds: Seeds one per fruit.