Rice is a cereal crop – a member of the grass family, Graminae. This family is divided into a number of genera (subfamilies), one of which is Oryza. This genus is further divided into a number of sections. One of them is sativae. There is a further subdivision called series. The rice grown in Asia is of a series sativa and its botanical name is Oryzasativa
Family: Graminae; Genus: Oryza; Section: sativae; Series: sativa.
Three most common sub-series of Oryza sativa are Japonica, Javanica and Indica.
Japonica is found in a more moderate climate of Japan and Korea. It is mostly grown and consumed domestically. It can be determined by it relatively shorter plant length and short, roundly rice grains. When cooked, its grains are moist and slightly sticky.
Javanica, one with a larger grain, is commonly found in Indonesia and the Philippines. Due to their low productivity, the cultivation of Javanica is limited to the place they were first discovered.
Indica likes warm, semi-tropical and tropical climate. It is the majority of rice that is grown in the other parts of Asia including India where they were first seen. Later some varieties of Indica rice were brought to America for the purpose of large scale farm production. Typical varieties of Indica rice are Thai HomMali rice (Jasmine), Basmati and most other slender long-grained varieties. So we can say that Indica is the world’s staple food.
Other two common series are Oryzaglaberrima and Oryzaofficinalis. The former is grown in Africa as human food while the latter are wild rice.
There are also a number of other series such as Oryzaspontanea, Oryzaperennis and Oryza from which Oryza Sativa, the world’s most widespread series, is believed to evolve. These, however, are of interest only to the botanists.
The complete hull consists of a lemma, a palea, an awn (tail), a rachilla (grain stem) and two sterile lemmas. Once grinded with light force, the husk easily breaks itself apart from the inner caryopsis. The husk is inedible but makes up approximately 20-25% of the total grain weight depending on the variety.
When rice grains turn golden-brown from green, it is ripe and the plant is ready for cutting. After the cutting, the rice is threshed to separate the grains from the rest of the plant and then winnowed. Winnowing takes the chaff away from rough rice (complete grains with hulls intact). Then rough rice is fed through a sheller to remove the husk to get brown rice. If brown rice is further milled to remove bran layers on the kernel, white rice is obtained.