Inch Plant (Tradescantia fluminensis)
Excellent pic!

Thanks Tiffany!
I'm wondering now whether I should move my pics, they look so similar and both species occur in the region I photographed them according to the Flora do Brasil.
I based my ID on this one which has a pic,
http://floradobrasil.jbrj.gov....
the other candidateTradescantia fluminensis has no illustration in that flora..
But it looks like you're familiar with both species..(unfortunately I didn't photograph more details of the plant..) I had no idea it had such a look-a-like..

Yes, I've had both plants for decades. Wiki has a great pic to compare. T. fluminensis:
https://commons.wikimedia.org/...

Daves has this great pic of G. geniculata. The flowers dangle on proportionately long peduncles and petals have a diff shape, leaves are purple on the back and are much smaller, has thin stems like a piece of wire:
http://pics.davesgarden.com/pi...

Thanks so much Tiffany!
You're explanation and links were very helpful!
I'm really convinced now! And thanks again!

Cool, happy to help you investigate! :+)