Emergent, erect, aquatic perennial herb to 1.5 m tall with a starchy rhizome. Leaves in tufts, linear, in 2 rows along the rhizome, parallel veined and 3-edged, purplish at first. Flower cluster an axillary cymose umbel with 3 bracts; summer. Flowers bisexual, regular, fragrant, about 2.5 cm wide, anthers and young ovaries dark red. Perianth in two whorls of 3 segments, the outer ones greenish, the inner ones pink. Stamens 6-9. Ovary inferior of 6 carpels that are open at the tip and united at the base and each containing numerous ovules. Fruit a whorl of separate follicles.
Source: (2005). Butomaceae. 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.