Alismataceae

Diagnosis: Aquatic herb. Leaves with large, sagittate laminas on elongate petioles to 1 m tall from a basal rosette. Inflorescence a paniculate scape to 2 m. Flower petals 3, free, white; gynoecium apocarpous consisting of numerous simple pistils. Fruits lanceolate achenes aggregated in globse heads originating from the apocarpous gynoecium.

Habit: Aquatic herb to ca. 2 m tall.

Main axis: Stem reduced, basal, or subterranean.

Leaves: Leaves simple, basal; petioles to ca. 1 m tall; lamina broadly sagittate, to 25 x 35 cm or more, the base deeply sagittate, the apex 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 2 m tall emerging from within the petioles of the basal leaves and up to 1 m above them.

Flowers: Flowers long-pedicellate, arranged in whorls of ca. 5-6 at regular intervals along inflorescence axis; the pedicel to ca. 2.5 cm long; calyx actinomorphic, sepals 3, fre, obovate, green; corolla actinomorphic, the petals 3, free, white, ephemeral; stamens 6, sometimes in two whorls of 3; gynoecium apocarpous of numerous simple pistils.

Fruit: Fruit lanceolate achenes clustered in tight globose heads originating from the apocarpous gynoecium.

Seeds: Seeds one per fruit.