Hylocereus undatus

Almost 20 years ago, while waiting for an order of Chinese Take out food on the corner of Ave. B and East 6th Street in The East Village, I noticed the slowly dying orchid cactuses that had looked so cool when the little place opened a year earlier.  I pinched a couple of branches and put them in soil in my apartment window. They began to grow and a few years later, the ceiling of the room they were in had turned into a real jungle of lush hanging orchid cactus branches.
One night I saw that they had developed buds. The buds got bigger over the next few weeks until one night, they started to open. The huge snow white flowers (6 to 7 inches across) open for one night.
In the jungles, the flowers are pollenated by bats. I didn't have any bats handy....

Dragon fruit for sale in a market.

When I moved to France, I took a few of the branches with me in my luggage. Now, I have another tropical jungle corner. The cactus is called a Night Blooming Cereus and is pretty spectacular. It bloomed this evening and here is a picture of one of the blooms. It has a scent and they really only last one night.
Because I have never pollenated the flowers, I never knew that they developed a fruit, but I have seen and bought the fruit in oriental markets for years. They are called Dragon Fruit or Pitaya...and have a taste like a kiwi. Only this evening, after taking the photos and doing a little reading did I realize that the Hylocereus undatus was the source of this rather spectacular exotic fruit...now, I'm going to try to pollenate them by hand and see what develops!