The most common frangipani in Australia, particularly around Sydney and Perth, is known as Plumeria rubra and often written P. rubra. The easiest way to describe a Plumeria rubra is to say if it looks like a common frangipani and it is NOT a Plumeria obtusa then it’s a Plumeria rubra.
Obsolete Plumeria Rubra Sub Species
There have been a variety of methods for grouping varieties within the P. rubra species but the latest news on Wikipedia, as updated by the experts, is that variations such as acutifolia (P. rubra f. acutifolia) and lutea (P. rubra f. lutea) are no longer the correct terminology.
Grouping Frangipani Flower Colour Groups
Most frangipanis are multicoloured and do not easily fit into a colour group however when flowers are viewed from a distant, the colours blend together and appear as a single colour.
The most logical groups seem to be cream, yellow, pink, red and orange.
The Arbitrary Nature of Colours
I’m not an expert in languages or foreign cultures but I’m sure these groupings are largely influenced from our western culture and the English language. For example, I think dark pink and light pink are quite separate on the colour spectrum but due to the English word “pink”, it’s easy to group them together.
When you add blue to the colour red, you get pinks and when you add more blue, you get colours such as dark purple and greyish purple. Since pure blue is rare in the world of flowers, shades of purple are usually called “Blue”. However, I think most children would call them purple or even pink more than blue. I think in English, purple and pink are closely linked so purple and blue frangipanis fall into the pink category.
The George Brown frangipani flower has, coincidentally it seems, a dominant brown or musk colour. When viewed from a distance, it often looks orange but sometimes looks pink.
Creating a brown, purple or even blue frangipani group is possible but since these groups would only have one or two flowers in them, it would defeat the purpose of grouping the flowers in the first place.
The Red-Rubra Theory
Since rubra means “red” in latin, it’s possible the original Plumeria rubra was pure red. Due to centuries of reproduction and the colour genes being modified, the number of frangipani flower varieties increased. Initially, if white was mixed with the red, the result would have been light pink flowers. Then, if yellow was mixed with the reds and pinks, the result would have been orange flowers. If eventually the red was completely lost, the result would be yellow and white flowers or completely yellow flowers.
On the opposite end of the colour spectrum, if some blue was mixed with red, the result would be dark pinks, purples and browns.
Cream or White
Many frangipani flowers are white with a yellow throat. From a distance, the yellow and white colours merge and the flowers appear cream. While many labels will read cream, I think both the close-up appearance and the sound of the word white is much more attractive.
At the opposite end of the spectrum to the common yellow and white flowers is the red frangipani flower. When red is mixed with white, the result is pink. When yellow is merged with pink or red, the result is orange. Most multi-coloured frangipani flowers have colour combinations like this and when viewed from a distance, appear orange.