In comparison: When I'm out and about with @CoMaps or another #OSM-based map, I can find good #freecamping / #wildcamping spots just by looking at the map, that's how much detail there is.
Mystery solved. The fruit is Brad's Atomic Grape. And the reason why it had potato leaves and large flowers is ... it came from a neighbouring plant. They had tangled up in each other I mistakenly thought it was a cross. Too bad, but clearly a cross waiting to happen!