Thanks Janet for the suggestion, I checked all the Gentianaceae in the region, no results..
maybe Campanulaceae..
We're also having sun, so I'm also going out!
No Balsaminaceae family registered in the Flora do Brasil Janet, though Impatatiens walleriana is very present everywhere over there.. It should be considered naturalized originating from Africa.
I know Janet! But anyhow just by browsing the images here and there with some families I found a couple of ID's..
I like very much the set-up of this site, with the index on the left and the images on the right, but it is still very incomplete, guess it has to grow with the years..
I did check the family Solonaceae Greene, all those I found looked to have alternate leaves. It seems some have opposite leaves towards the top though.
The leaves are generally alternate or alternate to opposed (that is, alternate at the base of the plant and opposed towards the inflorescence).