Need Help Identifying a Cutting Gift

[SteenAZ]

I was at a sort of gathering with some members of the Central Arizona Cactus and Succulent Society and touring a property when my friend Thom and I were told we could have cuttings from this sprawling and rather tall cactus growing under a tree. It was just too big and they were glad to give away pieces. I neglected to take a photo of the full plant but here is my cutting along with the fruit. It has four ribs.

[fanaticactus]

Possibly a Hylocereus.

[SteenAZ]

I doubt is is Hylocereus. This has 4 ribs not 3 and the fruit seems all wrong. Thanks for the suggestion.

[Pilif]

Acanthocereus tetragonus perhaps?

[SteenAZ]

The tetragonus is also another one of the three ribbed ones and this is 4.

[Minime8484]

Acanthocereus tetragonus can have anywhere from 3-5 ribs; as a matter of fact, "tetragonus" translates as "four angles/ribs".

[SteenAZ]

Interesting, I just skipped that as a possibility because I have a small one planted with three sides. I think this may be right. Now the question is what to do with this big cutting when rooted.