Maihueniopsis bonnieae, best known in cultivation as Puna bonnieae, is a small geophytic opuntioid that looks like a small Tephrocactus geometricus, but the bloom, fruit and the seeds clearly show its autonomous nature. During the dry season they are hidden in the ground. It forms slowly small cushion up to 15 cm in diameter.
Stems are small, usually globular, obconical to slightly elongated up to 2.5 cm tall and in diameter, they are broadly attached basally and do not detach easily from the mother plants. It is possibly an adaptation to high altitudes. They are dull blue-green but turns to dirty grey as they ages.