Since 2018 I have been studying basalt cactus Pediocactus nigrispinus as a retirement project at Wild Horse Wind Farm east of Ellensburg, Washington. This is Washington's only ball cactus, hence my username. Let me know if you would like links or PDFs of my articles below.
Pediocactus nigrispinus - Washington's Only Ball Cactus.
Phenology of Pediocactus nigrispinus in the Shrub Steppe of Central Washington.
Early Life History of Pediocactus nigrispinus in the Shrub-steppe of Central Washinton.