Oryza nivara is a possible wild progenitor of the cultivated rice Oryza sativa.[2][3][4][5][6] It was separated from Oryza rufipogon in 1965; however, the separation has been questioned,[7] and some sources treat it as a synonym of O. rufipogon.[8] It may be treated as the annual form of O. rufipogon.[2]
For those who accept it as a separate species, it is an annual, short to intermediate height (usually <2 metres (6 ft 7 in)) grass; panicles usually compact, rarely open; spikelets large, 6–10.4 millimetres (0.24–0.41 in) long and 1.9–3.4 millimetres (0.075–0.134 in) wide, with strong awn (4–10 centimetres (1.6–3.9 in) long); anthers 1.5–3 millimetres (0.059–0.118 in) long. It grows in shallow water up to 0.3 metres (1 ft 0 in), in seasonally dry and open habitats. It is found growing in swampy areas, at edge of pond and tanks, beside streams, in ditches, in or around rice fields.[5]
^Haritha, Guttikonda; Malathi, Surapaneni; Divya, Balakrishnan; Swamy, B. P. M.; Mangrauthia, S. K.; Sarla, Neelamraju (2018), Mondal, Tapan K.; Henry, Robert J. (eds.), "Oryza nivara Sharma et Shastry", The Wild Oryza Genomes, Compendium of Plant Genomes, Cham: Springer International Publishing, pp. 207–238, doi:10.1007/978-3-319-71997-9_20, ISBN978-3-319-71997-9