I have done a good amount of research on these and why they are called orchid cactus continues to elude me. They have been listed as epiphyllums, but the consensus is that they are misnames because the flower looks like it a separate plant from the leaves. Some say it's really a schlumbergera. Whatever! The flowers are big (about 3-4 inches long) and beautiful.
I took the photos below over a period of three days. This particular bloom was hidden at the back of the plant so I didn't get the first three or four days. The blooms open slowly, over six or seven days. The buds start as a funny little lump in notch of a leaf.
The leaves below the flower in the first photo are those of a Christmas Cactus.
Enjoy your day, and as always, thanks for stopping by............*s*