Nymphaea macrosperma

Nymphaea macrosperma is an aquatic annual or rhizomatous herbaceous perennial,^[3][5] with rounded rhizomes that lack stolons.^[6] The glabrous,^[5] orbicular, elliptic^[6] or suborbicular leaves^[7] with a dentate margin^[5][8] are 17–38 cm long, and 15–31 cm wide.^[5] The abaxial leaf surface has a strong midrib and 6 palmately arranged primary veins, which are reticulate towards the leaf margin.^[7] The petioles are up to 2.5 m long, and 2-4 mm wide.^[5]

The 6–7 cm wide,^[7] diurnal flowers extend above the water surface.^[8] The four^[7][6] oblong sepals with a rounded apex^[7] are 25-55 mm long, and 9-25 mm wide.^[5] The 10–18^[5](–22)^[6] white, blue, or purple,^[5] oblanceolate to spathulate petals^[6] have an obtuse apex.^[5] There is a conspicuous gap between petals and stamens.^[6][7] The androecium consists of 150–200 stamens. The gynoecium consists of 10–13 carpels.^[5] The 4 cm wide fruit^[6] bears oblong to ovoid,^[7] hairy, 3–4.5 mm long, and 2–3 mm wide seeds.^[6]

It was published by Elmer Drew Merrill and Lily May Perry in 1942.^[7][2] In the same publication, the species was described a second time as Nymphaea dictyophlebia Merr. & L.M.Perry, which is a synonym of Nymphaea macrosperma Merr. & L.M.Perry.^[9][2]

The type specimen was collected by LJ Brass in Lake Daviumbu, New Guinea (British New Guinea) in August 1936.^[10]

It is placed in Nymphaea subgenus Anecphya.^[11]

The specific epithet macrosperma means large-seeded.^[12][13]

It occurs in up to 2.5 m deep^[5] stagnant or flowing water^[3] in lagoons,^[7] swamps,^[5][7] billabongs, and drainage channels on clay substrates. It can occur in slightly brackish water.^[5]