I think many sites are showing the incorrect photo for the species Myriam! The photo of Allamanda oenotheraefolia you linked to was at least taken in a nursery in Brazil so is probably correct.
The plants of Hawaii should also have the correct plant, the flowers of Allamanda cathartica and schottii in these photos don't have a long tube.
http://www.hear.org/starr/imag...
http://www.hear.org/starr/imag...
Heights given on many web sites are often not correct either, they usually reflect what the plant might grow to in 10 years and in a different climate.
Alamanda oenotheraefolia has to be correct, good job you found a flower photo.
