Alismataceae

Diagnosis: Aquatic herb to about 20 cm tall. Leaves simple, tightly clustered in basal rosette, thin. Inflorescence of one or more short umbels. Flowers long-pedicillate; corolla of 3 free petals subtended by green calyx. Fruit an achene organized on a small globose head formed form an apocarpous gynoecium.

Habit: Aquatic herb to ca. 20 cm tall.

Main axis: Stems reduced to absent.

Leaves: Leaves simple, basal; petioles ca. 1-3 cm long; lamina oblanceolate, to 1.5 x 5 cm, thin, the base strongly decurrent on the petiole, the apex rounded, the margins entire, the venation inconspicuous.

Inflorescence: Inflorescence of one or more scapose umbels to ca. 20 cm tall emerging from within the basal leaves.

Flowers: Flowers long-pedicillate arranged in one terminal whorl of up to ca. 6; the pedicel ca. 3 cm long; calyx actinomorphic, sepals 3, free, ovate to lanceolate, green, alternate the petals; corolla actinomorphic, the petals 3, free, white to white-cream or yellow-white; stamens six; gynoecium apocarpous of six or more simple pistils.

Fruit: Fruit semi-globose, three-ribbed achenes clustered in loose globose heads originating from the apocarpous gynoecium; short style persistent at apex.

Seeds: Seeds tiny, one per fruit.