Minutes of the society's meeting (PDF).
One of the largest genera of succulents, and one of the weirdest.
One of the larger genera in the Cactus family, and one of the most variable.
From Mexico and Southern US. Usually having heavy spination and relatively small flowers, the fruits are copiously woolly. Includes the "Golden Barrel Cactus".
There are around 200 species in the genus, most from Mexico, some from the southern United States and into South America.