Janet, I checked out that Allamanda neriifolia and all the images that I could muster up with google. But it doesn't seem quite the same. However, not all the images that I googled up are all the same either. Perhaps it's been over cultivated and a lot of different forms/types have emerged.
The history of this plant is that a friend of the people who run the nursery brought it up from Perth, without a name. They just took cuttings and started selling it. When I suggested Allamanda they were a bit skeptical. They've got a friend in the business who according to them knows all there is to know about plants. They are going to ask him when he gets back from holidays.
If this one grows in Perth, that's a mediterranean climate, although watering could help it through. But it must be able to take non-tropical temperatures. Just don't know how low. Perth can get minumums down close to 0C
