This small plant with tiny white tubular flowers I found growing by the river in the rainforest.
Who am I?

I would look in Gentianaceae Myriam, for the moment I have to go outside with the camera, we have sunshine!

http://reflora.jbrj.gov.br/jab...

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!

The leaves remind me of Impatiens, have you checked Balsaminaceae?

Taking a very short break, insects are turning up and the sun actually feels HOT today!

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.

No results either in the Campanulaceae family..
The sun comes and goes over here and it is very windy and chilly!

I've done a lot of searching Myriam, I can't find it but some with similar leaves and flowers are in the family Rubiaceae which has a large presence.

I went through many pages on this Kew site then gave up and looked in Rubiaceae.

http://www.kew.org/science/tro...

Thank you Janet!! Great link to the Kew.org site, it can be very helpful for others I still need an id for!
I'll have a better look at it tomorrow..

There's 4,600 genera Myriam!

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..

Could it be something related to Nicatainia?

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).

http://en.wikipedia.org/wiki/S...