Maybe you have eaten one of these? Every now and then you can find them at the supermarket for 8$ a piece. The skin is bright fuchsia and the inside is pure white with black seeds. They are very striking.
The fruit (also called pitaya) grow on long slender branches of the cactus around a woody trunk.
I have been growing this plant from seeds taken from the last dragon fruit that I ate. Most (if not all) of the seeds planted germinated, and this happened very fast. Keeping them moist, they continue to grow surprisingly quick.
What amuses me about these seedlings are their two cotyledons (seed leaves). Being a cactus of it's particular sort, these are the only leaves this plant will ever have - a nod to it's heritage as a dicot (one of the two major groups of flowering plants) much like our embryonic gill slits are a nod to ours.
It will be several years before these cacti are ready to produce large night-blooming flowers, and bear fruit.