Mostly perennial aquatic and marsh herbs, sometimes annual or perennial depending on whether the water is permanent or not. Stems corm-like or stoloniferous. Juvenile leaves are mostly bladeless and submerged. Mature leaves mostly exposed, with linear to ovate or arrow-shaped blades and sheathed stalks. Flower clusters in racemes or branching, often whorled. Flowers bisexual or unisexual, regular. Sepals 3, green, persistent in fruit. Petals 3 or absent, soon shed, mostly white or pink. Stamens (3)6(9)-many, free. Ovary superior. Carpels 3-many, mostly free, containing 1-2 ovules. Fruit a head of achenes.
Used as ornamentals in ponds and pools or as aquarium plants. Superficially reminiscent of the dicotyledonous family Ranunculaceae. Closely related to the Limnocharitaceae.
13 genera with 70-100 species. Cosmopolitan, primarily freshwater swamps and streams in temperate and tropical Northern Hemisphere. Australia has 3 native genera and 2 naturalised genera.
Sagittaria sagittifolia is cultivated in Asia for its edible corms.
Mature leaves differentiated into blade and petiole and often with a milky sap; flowers in false whorls; ovary superior; carpels 6-many, separate, each with 1(2) ovule. Native plants occasionally offered include; Alisma plantago-aquatica L.,Water Plantain from NSW and Vic (distinguished from the naturalised A. lanceolata With. by having leaf bases rounded to cordate, not narrowed); Damasonium minus (R. Br.) Buchenau, Star Fruit, from all states and with characteristic star-shaped aggregate fruits.
Source: (2005). Alismataceae. In: . Horticultural Flora of South-eastern Australia. Volume 5. Flowering plants. Monocotyledons. The identification of garden and cultivated plants. University of New South Wales Press.