Why do you think it is not a cucumber? Looks like one to me......

Well, the flowerbuds are each about 2" long. There are other kinds than I planted, so maybe it is one of those. I guess time will tell.

I would have guessed a small size summer squash first. The flowers and stems seem large but hard to have perspective. Is it supposed to be a bush type cucumber?

You are correct, robert567. The opened flowers are 4" across whereas the cucumber is 1.5". The leaves are also larger. I'm tempted to pull it, but then again... I want to see what it is. Curiousity over what-needs-to-be-done.

FYI: The cucumbers are vines and growing upwards rapidly. Unfortunately, there is aready too much in this pot. Multiple potato plants emerged along with the cucumber and Ground Cherries. I moved all the Ground Cherries and had hoped for the best; now, who knows what else will come up volunteer in that pot.

Looks like only male flowers so far, might end up being a gourd of some sort?

That's a bummer, sorry. At least it would be for me since I live for my cucumbers. Is it too late to plant them?

AHA! I was rooting thru' the vines and discovered that the Griller Zucchini have exactly that same 3-flower thing going on. I'm thinking that this will be a zucchini. Since I already have a pot of these, I pull the stray.

Thanks for all your ideas! This was/is a mystery because I still don't know how that plant got into that pot. ( Garden Fairies no doubt. 🧚‍♀️)

Definitely a squash. Squirrels probably did it; they have a pathological hatred of anything in pots, and seem to enjoy playing evil tricks on gardeners. That, or one of your fingers was throwing a tantrum the day you were planting. ;-)

I was planning on pulling this one today, but discovered that it has set fruit; and it is the only one so far. And I'm ready for that zucchini. Rats!

I wonder if giving that pot extra-often fertilizer will compensate for lack of room. It's going to be a tight squeeze. At least the cucumbers will go up the trellis and get out-of-the-way.... but then there's the roots.

Bright green to the left is the stray zucchini squash; the middle is about a dozen potato stems from various unknown sources; and to the right is the cucumber in the back and forefront. Oh, and there are suddenly small Ground Cherry plants peeking out. What a pot! Good thing it is quite large.

cucumber has smaller flowers.