Acanthocalycium Thionanthum ssp Thionanthum
Usually solitary or slowly branching through basal shoots.
Spherical, over time it becomes slightly cylindrical, growing to a height of 12 cm or more, and a diameter of 6 to 10 cm. The epidermis is green to dark blue grey, and become a clear powdery-grey in the older part of the stem.
Bell-shaped, 5 cm. long or less on lateral areoles, and the segments of the perianth are sulphur or lemon-yellow or orange.