Euphorbia pentagona check the flower colour

There is a curious flower colour issue concerning Euphorbia pentagona that bothers some amateurs, including this one! Yellow-green flowering plants, as well as purple and mauve flowering ones bear this name. Can both be right? Sources don’t tend to mention both colour forms, or leave out reference to cyathia colour completely. The confusion may be resolved by the professionals later. Maybe both colours will occur officially.

On the plant in picture several inflorescences are stalked, branched and angled out from about every upper stem-tip. They deliver exuberantly in the yellow-green category in Kirstenbosch under the name concerned (Pooley, et al, 2025; iNaturalist; Wikipedia; https://www.llifle.com).