Oryza sativa L.
There are only two species of cultivated rice in the world: Oryza glaberrima, or African rice, grown in West and Central Africa and Oryza sativa, or Asian rice, grown worldwide.
Currently, however, the African rice (O. glaberrima) is fast being replaced by the higher yielding Asian rice varieties, so most of the rice in cultivation today, is Asian rice (Oryza sativa).
The genus Oryza contains 22 species: as mentioned above, only two are cultivated and 20 are wild.
The Asian Rice (Oryza sativa)
Etymology: ‘Oryza’ is a classical Latin word for rice. ‘sativa‘ means ‘cultivated‘.
There are many cultivar groups of Asian rice (Oryza sativa) of which the two most important are O. sativa ‘Indica’ and O. sativa ‘Japonica’.
The characteristics of the two cultivar groups have become less distinct because of the interbreeding programmes in recent years.
O. sativa ‘Indica’
O. sativa ‘Indica’ produces the fragrant non-sticky long-grain rice like Basmati, and is grown mostly submerged, in tropical lowland areas such as southeast Asia and the Philippines,
The grains of fragrant long-grain ‘Indica’ rice are high in amylose (a non-glutinous starch) and tend to remain intact after cooking and are perfect for stir-fries, sauces, pilau and curries.
Examples of long grain rice (at least three times longer than wide) include: basmati, jasmine, Patna, Carolina, or Texmati
O. sativa ‘Japonica’
O. sativa ‘Japonica’ produces the sticky short-grained rice and is cultivated in dry fields, in temperate areas of high elevations including Japan and northern China.
The grains of the short grain ‘japonica’ rice are high in amylopectin (a glutinous starch) and in general acquire a creamy, sticky texture and are good for risotto, rice balls, croquettes, crackers, cakes or as a thickening agent for sauces and puddings.
Examples of short grain rice (more or less round) include: sushi rice (ordinary Japanese rice, or uruchimai),
Examples of medium grain rice (less than three times longer than wide) include: bomba, carnaroli, arborio, vialone, Calrose, Valencia or Thai sticky rice, to name a few
Please note that short and medium grain rices are often combined into one category.