Barrel cacti are classified into the two genera Echinocactus

Echinocactus

Echinocactus is a genus of cacti in the subfamily Cactoideae. The generic name derives from the Ancient Greek εχινος , meaning "spiny," and cactus. It and Ferocactus are the two genera of barrel cactus. Members of the genus usually have heavy spination and relatively large flowers...

 and Ferocactus

Ferocactus

Ferocactus is a genus of large barrel-shaped cacti, mostly with large spines and small flowers. There are about 30 species included in the genus. They are found in the southwestern United States and northwestern Mexico. The young specimens are columnar but as they grow older ribs form and they take...

, both of which are found in the Southwest Desert of North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. Their pineapple-shaped fruits can be easily removed but are not recommended for eating. The barrel cactus may reach over a metre in height. Its ribs are numerous and pronounced and the spines are long and yellow. Small yellow flowers appear around the end of the plant only after many years.