Montanucci R. R., Kleszewski K. P., A taxonomic evaluation of Astrophytum myriostigma var. nudum (Cactaceae), Journal of the Botanical Research Institute of Texas, 2020, 14(2):255-264, doi: 10.17348/jbrit.v14.i2.1006
The paper analyses the rank of the nudum form within Astrophytum myriostigma. It discusses variation in stem hair cover and its significance in classification.