This plant I found growing on a rock by the riverside. Remarkable about it is the thickened base where the leaves emerge from. Could it be some kind of palm maybe?

The leaves do remind me of a palm Myriam, but the thickened bases remind me of a pseudobulb as you find on some orchids!

http://www.gardeningpakistan.c...

http://orchidsofmexicoandguate...

You're definitely right Janet, it must be a pseudobulb plant, originally when searching the web I came upon Pabstia modestior, which is an Orchid from Brazil,
https://www.google.be/search?q...

The bulbous base where the flowers sprouts from had the same shape, but in my plant there were at the base of the leaves, so I quitted that option..

There are three species of Pabstia recorded ( Flora do Brasil) in the Rio de Janeiro state:
Pabstia jugosa
Pabstia placanthera
Pabstia viridis

The photos I found of Pabstia placanthera don't show that bulbous leaf lase.
Pabstia jugora has them but the plant looks too small..
https://www.google.be/search?q...
Pabstia viridis is the only possible but I cannot find a detailed photo of the bulbous base.
The flowers look gorgeous of that one, a pity mine wasn't in bloom. But I still don't have an idea of the size of the plant..
https://www.google.be/search?q...

Pabstia viridis does show a pseudobulb much like the yours Myriam, look at the left pseudobulb. The flowers are gorgeous, as you know I love green flowers!

http://commons.wikimedia.org/w...

https://orchid.unibas.ch/phpMy...

Pabstia jugosa is illustrated on plantillustrations, the pseudobulbs look smooth, so do those on Pabstia placanthera. This type of bulb does wrinkle with age but yours are new growth and the ridging isn't wrinkling.

http://plantillustrations.org/...

It's a shame it wasn't in flower!

So I think we can come to the conclusion that mine is Pabstia viridis, Janet!
Thanks a lot for your assistance!
I know you love green flowers!

I have been jumping too fast to conclusion!
At that time I even knew less about orchids than is the case now.

After 7 years, I have been back to that very same rock during my recent trip and found the plant still there only bigger now. It was at the end of its blooming time, but I found a last flower stalk and many seedpods.
The shape of the bloom made it clear it couldn't be Bapstia.

And I found its true identity which is Gongora bufonia, being the only Gongora sp. in that area according to the Flora do Brasil.
http://floradobrasil.jbrj.gov....
The photo's match my plant.