Citrus species are small evergreen trees or shrubs growing to between 5 and 15 meters (15-45 feet) in height. Apparently native to northeast India, Myanmar and the Yunnan area of China, they have been introduced into cultivation around the world, primarily in subtropical and tropical regions. They are generally not frost hardy.
Citrus species hybridize readily and most species recognized are probably of hybrid origin, and only known from cultivation. Plants of the genus (oranges and pummelo) have been cultivated for at least 4400 years in China. This long history of cultivation and their easy hybridization confuses the issue of their native origin.
Also because of their easy hybridization, all commercially available varieties are reproduced through grafting.
Citrus fruits are known for their fragrance, and their high citric acid content which gives them a tangy flavor. They are eaten by humans either directly or used in preparing many dishes.
The plants require at least 25 cm/yr (10 in/yr) rainfall to be planted without irrigation. They have a fairly shallow but wide root system to collect water from their surroundings.
In addition to fruit consumption, all species are used in traditional medicine and their wood is used in crafts and for fuel.