It cannot be an Alocasia as this genus doesn't occur in Brazil.

There are 4 species of Xanthosoma registered in the Atlantic rainforest of the Rio de Janeiro state.

Xanthosma maximilianii
Xanthosoma pentaphyllum
Xanthosoma taioba
Xanthosoma riedelianum

It is none of the first 3, unfortunately I cannot find any photos or even herbarium species of X.riedelianum on the web.

The plant was growing in the shade on a very steep, almost vertical slope with a stream underneath heading to the river. It was difficult to take good photos as I had to stand on the crumbling edge of the slope, the plant was tall, and I found the leaf shape interesting, different from the other species I've met during this trip or my previous trip 4 years ago.

I'm not entirely sure but I think it had the beginning of an inflorescence coming up. A pity I couldn't come closer by and take better and more detailed shots.
In the hope to find a bloom about week later, I returned to the same spot, but alas the poor plant had been destroyed by a heavy monsoon, it had probably been washed down and taken by the stream. What a shame!

I searched for the subspecies of Xanthosoma brancoanum which (Xanthosoma riedelianum var. brancoanum) is listed as a synonym of Xanthosoma riedelianum on the Plant List Myriam.

http://www.theplantlist.org/tp...

I found a specimen of that which is on Kew, you can't enlarge it but it doesn't look correct.

http://plants.jstor.org/specim...

There's drawings of leaf shapes of Xanthosoma species on plantillustrations, you can see how difficult it is..

http://plantillustrations.org/...

Found this when googling re: Xanthosoma riparium:

http://www.cabdirect.org/abstr...

http://www.jstor.org/discover/...

And, this says Xanthosoma sagittifolium grows in Brazil:

http://www.ncbi.nlm.nih.gov/pu...

Thanks Janet! No it doesn't look like the herbarium sp on Kew of Xanthosoma riedelianum.
I know it would be very difficult, but can I call it Xanthosoma sp. or are there other genera that could be candidate?

Thanks Lin, I'm sure it isn't Xanthosoma saggitifolium and Xanthosoma riparium (Central Brazil) has not been registered in the place I was which is the South-East of Brazil at least according to the Flora do Brasil.

This site says X. sagittifolium is popular in several states in Southeastern Brazil: http://www.worldcrops.org/crop... but I guess it's not a native.

Maybe you can put your photo's in the general Xanthosoma entry in the database until you can get an exact ID.

Yes I know Lin, Xanthosoma sagittifolium is also growing in the place I was and I had already submitted photos of that plant from my previous trip, but the plant I posted here is really different and cannot be it.
I was planning to put the photos into the general Xanthosoma page but wanted to make sure it is the correct genus.

It sure is pretty and looks to have the form and growth habit of Xanthosoma. I love that tall (Bird of Paradise?, Palm?, Musa?) plant growing in the background too!

It is Musa paradisiaca Lin, native to Brazil.
I love banana trees, they are very beautiful, so generous to so many species of wildlife!

bonitin said:Thanks Janet! No it doesn't look like the herbarium sp on Kew of Xanthosoma riedelianum.
I know it would be very difficult, but can I call it Xanthosoma sp. or are there other genera that could be candidate?

To me, it looks like a Xanthosoma sp., the leaves are very similar to the line drawings. If it turns out to be something else it can be moved but I doubt it is something else.

Thanks Janet, Xanthosoma sp. it will be for now..