The one photo of Senna spectabilis var. excelsa in which you could see the leaves behind the flowers did look correct to me too Myriam, but the fuller shots showed longer leaf stems. I haven't been able to find any other photos of it.
http://www.flickr.com/photos/m...
Senna corymbosa has shorter leaf stems.. but they are only up to 3m tall according to florasbs
http://sites.google.com/site/f...
