DYCKIA BURLE MARXII ?
(Another nebulous species.
Our science takes ages to decide.)

It gets the distal two thirds of the leaves purple when in a drier situation. The plant comes from Central Brazil and it is one of the most sought after plant among Dyckia keepers. When in full coloration it is a sight to behold.Rare and beautiful. In nature it is so high on a perpendicular Cliff wall that it is impossible to get there without being a skilled alpinist. The field scientists collectors really on plants that grown way down in the grass field by fallen and gone with the wind seeds and left intact by the cattle and soy farms down below.