What's the background history, and origin of this plant. It's definately in Convolvulaceae, and looks like a native North American species, like Stylisma. I can't find any Australian species in Convolvulaceae that match?

Thanks for your reply. My first thought was that it was some weird kind of morning glory. About 7 years ago, I grew a Heavenly Blue one. I’ll attach a pic. Although I was scrupulous about deadheading the flowers every day, the next year, some seedlings of it sprang up. The flowers were much smaller and paler, and I pulled them all out. Could this little white thing possibly be a mutated descendant? The flower shape is unlike that of the original m.g. flower, and this one has started flowering in mid-winter here, whereas the blue one flowered only in autumn. I can’t see any images of this little white flower on the internet. Most ipomeas are viewed with great disfavour - horror - in Australia.

Heavenly Blue is a hybrid, but I cant find any information about what species were crossed in the breeding that created it. It would have to be a species that has fleur de lis shaped leaves, because Heavenly Blue has heart shaped leaves. The offspring may resemble each of the parents.