Hydrocera triflora belongs to family Balsaminaceae, the same family that the balsams (Impatiens) belong to. It is the only member of the genus Hydrocera. It is commonly known as water balsam or marsh henna and Malays call it ‘inai paya’ (swamp henna). The species is native in lowland areas stretching from India, Sri Lanka, Southern China, Indo-China, Thailand, Peninsular Malaysia to Indonesia. Hydrocera triflora can be found in still or stagnant, shallow water in rice fields, wetlands and swampy areas.

Hydrocera triflora is a semi-aquatic succulent herb, erect, up to 1 m tall with a glabrous, angled stem with many branches. The portion of the stem above the water is leafy, whilst the submerged portion is much thickened and spongy in texture. The leaves are alternate, sessile or shortly petiolate and the lamina is narrowly lanceolate with a pointed apex and toothed margin. The lower lamina surface is pale green. Hydrocera triflora has 1-3 flowers together in short bunches from the leaf-axils. The pretty flowers are pale pink to crimson-pink with white and yellow markings. It has five free sepals and petals. The globose, indehiscent berry at maturity turns purplish red, is c. 1 cm in diameter and normally is 5-seeded.

The flowers of Hydrocera triflora yield a red dye that can be used to prepare a dye for fingernails and which serves as a substitute for henna (Lawsonia inermis), hence its common Malay and English names, but, as far as I know, it had not been used in this way in Peninsular Malaysia.