Dragon Fruit

Dragon fruit is the fruit of several cactus species from the genera Hylocereus and Selenicereus. The fruit came from Mexico, Central America and South America but now cultivated in Asian countries like Taiwan, Vietnam, Philippines, and Malaysia. Fruit can also be found in Okinawa, Israel, northern Australia and southern China. Hylocereus blooms only at night.

In 1870 this plant was brought French people of Guyana to Vietnam as an ornamental plant. By Vietnamese and Chinese men is considered a blessing. Therefore, the fruit is always placed between two small green dragon statue above the altar table. Fruit red color looks striking in the color green dragons. From this habit of fruit was among the Vietnamese who greatly influenced Chinese culture known as the thang Loy (dragon fruit). The term Thang Loy then translated in Europe and other countries who speak English as a dragon fruit (dragon fruit)

Ref :
http://id.wikipedia.org/wiki/Buah_naga