Oryza sativa (rice) is a monocotyledonous flowering plant of the family Poaceae and is one of the most important crop plants in the world, providing the principal food source for half of the world's population.

Oryza sativa subsp. japonica is one of three major subspecies of rice, the others being indica and javanica. Oryza sativa subsp. japonica is short-grained and high in amylopectin so that the grains stick together when cooked, which distinguishes it from subsp. indica which is long grained and not sticky.

Oryza sativa subsp. japonica is grown in dry fields, mainly in temperate or colder climates such as Japan.

Oryza sativa has a haploid chromosome number of 12, containing 370 Mb with 30,000 protein-coding genes. Rice was an obvious choice for the first whole genome sequencing of a cereal crop. It is the smallest of the major cereal crop genomes and is the easiest to transform genetically. The cultivar sequenced from the japonica subspecies was Nipponbare (www.thericejournal.com/content/6/1/4/abstract).