It called my attention because of the bright green and striped leaves, it seemed to creep..
I had put it with the grasses folder and searched in the Olyra genus because of the likeness.
https://www.google.be/search?q...

but I don't think so now .. it has something ginger-looking too, the way the leaves are attached to the plant stem, I couldn't find anything though in the zingiberaceae..

maybe in the Commelinaceae..
Unfortunately no flowers..

Maybe it's a dwarf bamboo?

https://www.google.co.uk/searc...

Maybe not, the leaves clasp the stem which could indicate a ginger, or another unknown plant.

Could be in Commelinaceae ..

https://sites.google.com/site/...

Dichorisandra angustifolia looks similar but I can't get Flora do Brasil to check. It looks to have raised rings on the stem where the leaves attach.

http://fm2.fieldmuseum.org/pla...

https://www.flickr.com/photos/...

I don't know Janet if Gingers can make side shoots on the main plant stem?
(The flora do Brasil also doesn't work for me..)
A crop..

Wavyleaf Basket grass?

porkpal said:Wavyleaf Basket grass?

That looks like it!

http://www.nps.gov/shen/learn/...

Oplismenus hirtellus ssp. undulatifolius

http://www.nps.gov/shen/learn/...

It's not a native of Brazil ..

https://en.wikipedia.org/wiki/...

Kew only lists, apart from other locations, "South America: Caribbean" but it certainly looks like it.

http://www.kew.org/data/grasse...

I feel sure it is Oplismenus hirtellus ssp.undulatifolium !
A grass after all then!
I have only met it once, I hope it is not going invasive in the Atlantic Forest!
As the winters are so mild over there, if would even not lose it foliage, spreading much quicker than in areas with cold winters!
Thanks Porkpal for finding it and Janet for your much appreciated in-depth assistance as always!

In my case the assistance is more a matter of luck than botanical research.