Oryza is a genus of plants in the grass family. It includes the major food crop rice (species Oryza sativa and Oryza glaberrima). Members of the genus grow as tall, wetland grasses, growing to tall; the genus includes both annual and perennial species.

Oryza is situated in tribe Oryzeae, which is characterized morphologically by its single-flowered spikelets whose glumes are almost completely suppressed. In Oryza, two sterile lemma simulate glumes. The tribe Oryzeae is in subfamily Ehrhartoideae, a group of Poaceae tribes with certain features of internal leaf anatomy in common. The most distinctive leaf characteristics of this subfamily are the arm cells and fusoid cells found in their leaves.

One species, Asian rice (O. sativa), provides 20% of global grain and is a food crop of major global importance. The species are divided into two subgroups within the genus.

Species

Inside the genus Oryza, species can be divided by their genomes types (listed after each species name below). They include the diploid (2n=24) of cultivated rice and their relatives, , , , and as well as the tetraploid (4n=48) , , , and . Species of the same genome type cross easily, while hybridizing different types requires techniques like embryo rescue.

Over 300 names have been proposed for species, subspecies, and other infraspecific taxa within the genus. Published sources disagree as to how many of these should be recognized as distinct species. The following follows the World Checklist maintained by Kew Garden in London.

• Oryza australiensis (EE) – Australia

• Oryza barthii (AA) – tropical Africa

• Oryza brachyantha (FF) – tropical Africa

• Oryza coarctata (KKLL) – India, Pakistan, Bangladesh, Myanmar

• Oryza eichingeri (CC) – tropical Africa, Sri Lanka

• Oryza glaberrima (AA) – African rice – tropical Africa

• Oryza grandiglumis (CCDD) – Brazil, Venezuela, Fr Guiana, Colombia, Peru, Bolivia

• Oryza latifolia (CCDD) – Latin America + West Indies from Sinaloa + Cuba to Argentina

• Oryza longiglumis (HHJJ) – New Guinea

• Oryza longistaminata (AA) – Madagascar, tropical + southern Africa

• Oryza meyeriana (GG) – China, Indian Subcontinent, Southeast Asia

• Oryza minuta (BBCC) – Himalayas, Southeast Asia, New Guinea, Northern Territory of Australia

• Oryza neocaledonica (GG) – New Caledonia

• Oryza officinalis (CC) – China, Indian Subcontinent, Southeast Asia, New Guinea, Australia

• Oryza punctata (BB) – Madagascar, tropical + southern Africa

• Oryza ridleyi (HHJJ) – Southeast Asia, New Guinea

• Oryza rufipogon (AA) – brownbeard or red rice – China, Indian Subcontinent, Southeast Asia, New Guinea, Australia

• Oryza sativa (AA) – Asian rice – China, Indian Subcontinent, Southeast Asia; naturalized many places

• Oryza schlechteri (HHKK) – New Guinea

Formerly included

Many species are now regarded as better suited to other genera:

• Echinochloa

• Leersia

• Maltebrunia

• Potamophila

• Prosphytochloa

• Rhynchoryza

See also

• Specialized metabolism in Oryza

References