Id please

Just a suggestion..may be miles out.
Nicandra physalodes.

nicandra physalodes leaves - Google Search:

 

Does have that Datura look about it.
A flower would clinch it.

 

If its Nicandra, it should have lots of tiny purple dots (hairs) on the leaf.

 

Thanks PeterS valid point.
I noticed these just last week.See pic.
These rarely show up on pics on www

Apparently The black 'dots' are actually the black bases of transparent trichomes (stiff glandular hairs). They exude a sticky substance which is a strong contact-adhesive and can be absorbed through the skin to cause hallucinations.

 

That's interesting Silver Surfer, I never knew Nicandra could be hallucinogenic - but then there are many more poisonous and hallucinogenic plants than we realise.