@piggo This really looks like a kind of cucumber. Your 3rd leaf and the 3rd leaf on the sample pic look very much alike.
@FailForward That was a good call, I looked at the genus listing and found what it is!
*Echinocystis lobata*
*Echinocystis lobata*
@piggo There you go. I was thinking the same, but the locality does not match. The botanist I asked about your pics told me this is probably some non-European plant, but I gather you collected it in CZ (or around), right? So it's some import which went wild...
And indeed, [Wikipedia says](https://en.wikipedia.org/wiki/Echinocystis#Distribution) it's an invasive species in E/SE Europe:
> It has also been reported as an uncommon invasive species in the Örség Landscape Protection Area of Hungary near the Austrian-Slovenian border.
If the fruit matches, you've got it. 
@FailForward yep, the fruit is right. I saw it grown before, but that was maybe 5-10 years ago. Too bad the fruit is not edible. well, i might try it anyway 
ftr, the seeds were collected around 49.9958372N, 14.0224308E
ftr, the seeds were collected around 49.9958372N, 14.0224308E
