Astrophytum caput-medusae

This species differs from the conventional star-shaped phenotype associated with other Astrophytum members. It has a very reduced, shortly cylindrical stem that lacks ribs. The stem collar and apex is covered in paper-like bristles that originates from the basal rest of tubercles. The bristles are coffee-colored with reddish tones. A taproot is formed. The tubercles are cylindrical (occasionally triangular when young), of cartilaginous consistency, smooth, growing up to 19 cm in length and 0.2-0.5 cm in width. Tubercles are glaucous-green in color, almost totally covered with greyish-white trichomes. It grows up to 4 spines of 0.1-0.3 cm in length that generally persists on old tubercles. The flowers grow on the developing sections of the tubercles. It is yellow with an orange-colored base. Outer segments are greenish yellow, and covered with white hairs and spines. Fruits are green and fleshy, drying as it ripens. Seeds are cap-shaped, dark coffee or black, and measures up to 0.3 cm.

A. caput-medusae is native to Mexico, specifically the state of Nuevo León. The plant is reportedly found growing wild only at a single location.