Ornduffia umbricola, also known as the lax marsh-flower, is a species of plant in the Menyanthaceae family of wetland plants that is endemic to Australia. There are two recognised varieties.
The species is a slender, tufted, perennial (occasionally annual) herb that grows up to 105 cm in height. The round leaves are 1âÂÂ12 cm across. The yellow flowers are 11âÂÂ31 mm in diameter with 4âÂÂ6 (usually 5) lobes. The seed capsules are 5âÂÂ11 mm long. The flowers and fruits appear mainly from November to April.
The species occurs in western Victoria, south-eastern South Australia and Tasmania. It is found in semi-shaded sites on damp sandy or peaty soils, or in shallow freshwater wetlands, sometimes in water up to 45 cm deep.