I've had this plant for about 5 or 6 years, and it was a cutting from a plant that is now, I think, 20 years old. It has neither flowered nor fruited as long as I have been growing it. Is this specimen a dragon fruit? This picture makes it look flat, but it is not; it has three fleshy flanges on each part of the plant. This link should take you to my photobucket where I have a second photo. My plant looks so similar to other pitaya photos I've seen, I can think of nothing else that it could be.

If this is indeed a dragon fruit, how do I get it to flower?

http://i488.photobucket.com/albums/rr243/zach_godel/DragonFruit002.jpg?t=1269398644

Here is a link that might be useful: Dragon Fruit?