Aloe mutabilis is closely related to A. arborescens, sometimes classified as just another form. Its spectacular feature is the clinging to steep cliff edges, hanging high above water or over deep, shady ravines. There is said to be a form in Mpumalanga bearing pure red flowers, i.e. the perianths do not turn yellow upon opening.
The human habit of separating things that display small differences into discrete categories, or conversely, lumping them together when limited similarity is found, has found its way into the biological sciences where one species may imperceptibly start to split as parts of its distribution confront different living conditions.
Since Aristotle, categorization has been an important part of scientific output, based on observation and analytical skills. And there are psychological characteristics to distinguish those people who focus on differences from those who focus on similarities.
We fortunately also learn how to build conventions and solutions for overcoming every kind of confusion caused by our lifestyle and experience. We call the story of that history.