orchid cactus Epiphyllum? Christmas cactus Schlumbergera or Zygocactus?

Possibly the orchid cactus Epiphyllum. It grows upright and does not flower. It's not a Christmas cactus for sure. Will post a better photo of the leaves. Thanks for the lead!

It's not flowering because it's not getting what it needs to flower, not because it's a plant that never flowers. From the appearance of the foliage it looks like it's being kept as a house plant under ordinary indoor conditions. Moved into a brighter, more humid situation and a larger container, allowed to develop more fully it would probably soon start blooming.

The commonly grown, frequently asked about Epiphyllum that produces a percentage of flattened, paddle-like stem sections is E. oxypetalum. Because this one is so prevalent chances are that is what you have. Otherwise, without the flowers having been seen it seems the plant asked about here could just as well be something else. There are many species of epiphytic cacti in cultivation including those in other genera besides the three mentioned so far here.

https://www.bing.com/images/search?q=epiphyllum+oxypetalum&qpvt=epiphyllum+oxypetalum&qpvt=epiphyllum+oxypetalum&FORM=IARRSM

Thanks so much! And you're right. It was at one time kept in a friend's greenhouse and looked much happier. I gave it an indoor home when the friend moved and it's been a little neglected since. Perhaps it's time to rectify that!