The longan, literally "dragon eye" in Chinese, is a tropical tree native to southern China. It is also found in Southeast Asia.
The tree can grow up to 12 metres in height, and the plant is very sensitive to frost. Longan trees require sandy soil and temperatures that do not typically go below 4.5 degrees Celsius (40 degrees Fahrenheit). Longans and lychees bear fruit at around the same time of the year.
The longan ("dragon eyes") is so named because of the fruit's resemblance to an eyeball when it is shelled (the black seed shows through the translucent flesh like a pupil/iris). The seed is small, round and hard, and of an enamel-like, lacquered black. The fully ripened, freshly harvested shell is bark-like, thin, and firm, making the fruit easy to shell by squeezing the fruit out as if one is "cracking" a sunflower seed. When the shell has more moisture content and is more tender (due to either premature harvest, variety, weather conditions, or transport/storage conditions), the fruit becomes less convenient to shell.
To express longan fruit, there is a Vietnamese riddle: Da cóc mà bọc bột lọc, bột lọc mà bọc hòn than (literally: Toad's skin covers tapioca flour, tapioca flour covers coal stone): toad's skin is the skin, tapioca flour is the clear white flesh and coal stone is the black seed.
The fruit is edible, extremely sweet, juicy and succulent in superior agricultural varieties, and apart from ingested ...