Plant Description
Erect, tree-like cactus, usually with a stout trunk and ascending branches consisting of nearly round pads.
Distinguished from other Opuntia sp. by its well defined trunk, the scarcity of spines where areoles are mostly dense patches of yellow glochids with few yellow, generally deflexed spines; and the mostly orbicular pads.
Habitat
Found growing on very steep hillsides in mountainous terrain, also on mesas and dry, rocky desert walls.
Flowers
Flowers are 2-1/2 to 2-3/4 inches in diameter with petals about 1 inch long and 1/2 inch wide.
Stems
The pads of this prickly pear are almost perfectly round, 4 to 8 inches, giving rise to its common name.
Areoles
These are structures unique to cacti, found on the stems, areas from which spines, flowers and fruits emerge.
Crowded in narrow marginal crescent near the pad.
Mostly straight but can be weakly curved.
Fruit
Fleshy, reddish-purple fruit, 1 to 2 inches long, is not spiny.