When I got back from work yesterday as suspected there were a number of withered flowers on the ground. But there were also a lot of flower buds looking like they were ready to burst open. The plant itself, from a distance, was really looking more like a pumpkin patch, just the leaves a little smaller.
This morning, early, some of the buds were starting to open.
A bit later there were several flowers open.
So very definitely Convolvulaceae, although I doubt now it'd be Ipomoea. One other interesting emergent from the new soil was an Amorphophallus. It's out in the blazing sun so the leaves curl up. I'm going to put a bit of shade over it later which should make it real happy, after getting practically cooked every day.