Nuphar oguraensis is a species of rhizomatous aquatic plant endemic to Japan.
Description Vegetative characteristics The petiolate, green, ovate floating leaves are 7.5-11.5 cm long, and 6-9 cm wide. The petiole is 1-3 mm wide.Padgett, D. J. (2007). A MONOGRAPH OF NUPHAR (NYMPHAEACEAE). Rhodora, 109(937), 1–95. http://www.jstor.org/stable/23314744 The petiole is semi-hollow.Padgett, D. J. (2003). Phenetic studies in Nuphar Sm. (Nymphaeaceae): variation in sect. Nuphar. Plant Systematics and Evolution, 239(3/4), 187–197. http://www.jstor.org/stable/23645175 Generative characteristics The flowers are 1.7-2.5 cm wide. The 2.5-3 cm long, and 1.5-2 cm wide fruit bears brown, 3.5-4 mm long, and 2.5 mm wide seeds.
Reproduction Generative reproduction Flowering occurs from June to October.
Taxonomy Publication It was first described by Shigeru Miki in 1934.
Type specimen The lectotype is an illustration of this species in the original publication by Shigeru Miki.PADGETT, D. J. (1999). NOMENCLATURAL NOVELTIES IN NUPHAR (NYMPHAEACEAE). SIDA, Contributions to Botany, 18(3), 823–826. http://www.jstor.org/stable/41968902 Natural hybridisation It has been speculated to be of hybrid origin involving Nuphar pumila and Nuphar japonica.
Conservation It is threatened by urbanisation and land development. It is regarded as a vulnerable species.
Ecology Habitat It occurs in rivers, lakes, ponds, and ditches.
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