Regardless of genus or species, night blooming cereus flowers are almost always white, often large, and frequently fragrant. Most of the flowers open after nightfall, and by dawn, most are in the process of wilting. The plants that bear such flowers can be tall, columnar, and sometimes extremely large and tree-like, but more frequently are thin-stemmed climbers. While some night blooming cereus are grown indoors in homes or greenhouses in colder climates, most of these plants are too large or ungainly for this treatment, and are only found outdoors in tropical areas.
Cultivation and uses
Some night blooming cereus plants produce fruits which are large enough for people to consume. These include some of the members of the genus Cereus, but most commonly the fruit of the Hylocereus. The Hylocereus fruit have the advantage of lacking exterior spines, in contrast to the fruit of cacti such as the Selenicereus fruit, being brightly colored, and having a pleasant taste. Since the late 1990s, Hylocereus fruit have been commercially grown and sold in tropical locations like Australia, the Philippines, Vietnam, Taiwan, and Hawaii.
Around 2000, the name "Dragonfruit" was created for promotional purposes in English-speaking countries, undoubtedly influenced by the very successful renaming of "hairy gooseberries" as "Kiwifruit" earlier in the 20th century. The unusual exterior of a Hylocereus fruit, with its protruding growths, inspired the reference to dragons. Hylocereus fruits are also called pitaya. Increasing commercial cultivation, and the hybridizing of new varieties, is occurring for this fairly new crop. However, dragonfruit are usually somewhat expensive during their season (summer) and are still a specialty for most consumers.
Information VIA Wikipedia.org