From southern Brazil, Uruguay and Argentina, Parodia scopa ssp. scopa is a clumping globular cactus that eventually becomes columnar with age. The heads get to be as much as 4 inches across and 18 inches tall and it produces the typical yellow Parodia flowers.
     These came from Tanque Verde Nursery. I had two others that were even nicer from B&B but lost them both to rot.

Flowering in May

A closer view