It is true that the lower portion is of the same family but that does not mean the fruit would be good. You also would not know if it is self-fertile or requires another variety for pollination.

Named cuttings are fairly inexpensive and readily available on-line or from others who are growing the plants (which grow like weeds in favorable conditions). A better bet, IMHO.

Thanks for the info. I kinda figured that would be the case. I will save my $3.

Mike

Those aren't dragonfruit. I have around 15-20 df varieties at home. We can arrange a trade, just message me

The stock for the small "Grafted Moon Cactus" which are sold by those retailers is indeed Hylocereus. I've done exactly what you indended and while the stock may look strange, new growth is obviously Hylocereus.

That said, I agree that it is likely not self-pollinating and also would have garbage-quality fruit. I think its also a pretty safe bet that nearly all in not all of the Hylo stocks are undates, because its the most widely available/cheapest and whoever produces these grafted specimens probably isn't going to spring for a costaricensis or megalanthus.

The Hylocereus they sell once degrafted take FOREVER to recover and begin pupping, as the roots are totally overgrown for those pots and are all tangled up and compressed, which I assume is intentional and so that they are less likely to throw out random tendrils.
Definitely would recommend using that $3 instead as a chunk of your purchase of a named cutting. Some of my favorites are American Beauty, Physical Graffiti, and Halley's Comet, which are all very easily found. (I'm dying to try a Cosmic Charlie on that note, apparently also has awesome flavor)

The moon cactus is made by Hylocereus Ocamposis variety (I have this variety). Probably by other Halocereus as well. H. Ocamposis is not a self sterile, so it need a pollinator. If you have a good pollinator, it's fruit will be very good.