Bárcenas R. T., Hawkins J. A., Nomenclatural proliferation and the superabundance of Homotypic Synonyms in Grusonia (Opuntioideae, Cactaceae), Haseltonia, 2017, 23:27-34, doi: 10.2985/026.023.0104
The historical compilation of names in the Grusonia group shows how changes in generic placement produced successive homotypic synonyms. The authors distinguish an increase in the number of nomenclatural combinations from a change in the number of recognised species.