Notocactus buiningii

Also known as Parodia buiningii, generally it is a solitary cactus of a rounded shape, slightly flattened at the apex, with well-defined protruding ribs. The downy white areoles bear 5-7 long and rigid spines, of a light greenish color with brown shades at the base. Flowering occurs in summer, blooming with numerous large yellow flowers, that open up during the day and close down at night.