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 1–2 m 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.[verification needed]
Inside the genus Oryza, species can be divided by their genomes types. They include the diploid (2n = 24) AA of cultivated rice, BB, CC, EE, FF and GG as well as the tetraploid (4n = 48) BBCC, CCDD, HHJJ, HHKK and KKLL. Species of the same genome type cross easily, while hybridizing different types requires techniques like embryo rescue.
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.
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, India, Japan, Southeast Asia; naturalized many places
- Oryza schlechteri (HHKK) – New Guinea
Many species now regarded as better suited to other genera:
- lectotype designated by Duistermaat, Blumea 32: 174 (1987)
- "World Checklist of Selected Plant Families: Royal Botanic Gardens, Kew". apps.kew.org. Retrieved 2016-09-14.
- Linnaeus, Carl von. 1753. Species Plantarum 1: 333. in Latin
- "Tropicos | Name – Oryza L." www.tropicos.org. Retrieved 2016-09-14.
- "Oryza in Flora of China @ efloras.org". www.efloras.org. Retrieved 2016-09-14.
- Kellogg, E.A. (30 January 2009). "The Evolutionary History of Ehrhartoideae, Oryzeae, and Oryza". Rice. 2: 1–14. doi:10.1007/s12284-009-9022-2.
- Heywood, V.H. Flowering Plants of the World 1993 Oxford University Press
- Stein, Joshua C.; Yu, Yeisoo; Copetti, Dario; Zwickl, Derrick J.; Zhang, Li; Zhang, Chengjun; Chougule, Kapeel; Gao, Dongying; Iwata, Aiko; Goicoechea, Jose Luis; Wei, Sharon; Wang, Jun; Liao, Yi; Wang, Muhua; Jacquemin, Julie; Becker, Claude; Kudrna, Dave; Zhang, Jianwei; Londono, Carlos E. M.; Song, Xiang; Lee, Seunghee; Sanchez, Paul; Zuccolo, Andrea; Ammiraju, Jetty S. S.; Talag, Jayson; Danowitz, Ann; Rivera, Luis F.; Gschwend, Andrea R.; Noutsos, Christos; Wu, Cheng-chieh; Kao, Shu-min; Zeng, Jhih-wun; Wei, Fu-jin; Zhao, Qiang; Feng, Qi; El Baidouri, Moaine; Carpentier, Marie-Christine; Lasserre, Eric; Cooke, Richard; Rosa Farias, Daniel da; da Maia, Luciano Carlos; dos Santos, Railson S.; Nyberg, Kevin G.; McNally, Kenneth L.; Mauleon, Ramil; Alexandrov, Nickolai; Schmutz, Jeremy; Flowers, Dave; Fan, Chuanzhu; Weigel, Detlef; Jena, Kshirod K.; Wicker, Thomas; Chen, Mingsheng; Han, Bin; Henry, Robert; Hsing, Yue-ie C.; Kurata, Nori; de Oliveira, Antonio Costa; Panaud, Olivier; Jackson, Scott A.; Machado, Carlos A.; Sanderson, Michael J.; Long, Manyuan; Ware, Doreen; Wing, Rod A. (22 January 2018). "Genomes of 13 domesticated and wild rice relatives highlight genetic conservation, turnover and innovation across the genus Oryza". Nature Genetics. 50 (2): 285–296. doi:10.1038/s41588-018-0040-0. PMID 29358651.
- Ammi'Raju, Jetty; Song, Xiang; Luo, Meizhong; Sisneros, Nicholas; Angelova, Angelina; Kudrna, David; Kim, Hyeran; Yu, Yeisoo; Goicoechea, Jose; Lorieux, Mathias; Kurata, Nori; Brar, Darshan; Jackson, Scott; Wing, Rod (1 December 2010). "The Oryza BAC resource: A genus-wide and genome scale tool for exploring rice genome evolution and leveraging useful genetic diversity from wild relatives". Breeding Science. 60: 536–543. doi:10.1270/jsbbs.60.536.