These 3 genera, in the Crassulaceae family, include plants from many parts of the world.
Ariocarpus is one of the treasures of the world of Cacti, from Central to Northern Mexico and Southern Texas.
The Bromeliads, like Cacti and Agavaceae are a New World family.
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.