Thank you Janet!
I think I have found it! it is Epiphyllum oxypetalum.
The flower is gorgeous but it was not blooming the time I was there unfortunately. It is night-blooming and is called 'Dama da Noite'= 'Lady of the Night'.
My half-Brazilian friend has given me its popular name, should have asked her before!
There are more plants called that way but she recognized it by the flower.
http://search.babylon.com/imag...