The Collaborative International Dictionary
barrel cactus \bar"rel cac"tus\ (b[a^]r"r[e^]l k[a^]k"t[u^]s), n.; pl. barrel cacti (b[a^]r"r[e^]l k[a^]k"t[imac]). any of several large cacti native to the southwestern U. S. and Mexico, having a short cylindrical form with deep vertical ribs and bearing sharp spines. They are classed in the genera Ferocactus and Echinocactus.
Wiktionary
n. Any cactus with an approximately barrel-like shape.
WordNet
n. a cactus of the genus Ferocactus: unbranched barrel-shaped cactus having deep ribs with numerous spines and usually large funnel-shaped flowers followed by dry fruits
any cactus of the genus Echinocactus; strongly ribbed and very spiny; southwestern United States to Brazil [syn: echinocactus]
Wikipedia
Barrel cactus are various members of the two genera Echinocactus and Ferocactus, found in the deserts of Southwestern North America.
Usage examples of "barrel cactus".
There wasn't even a barrel cactus within sight, although this was the country in which they grew.
One small tree or bush, not unlike a barrel cactus, grew on the edge of the rocky wilderness.
Some barrel cactus were mixed in, but mostly it was all Devil Fork.
Anna could see each spine on the small barrel cactus growing at the edge of the shadow that hid her.
Here and there, a large barrel cactus stuck up from the floor like a bristling green thumb.
The barrel cactus has saved hundreds of desert travelers from dying of thirst.
One cactus plant after another appeared: clumps of straight spiky tubes, barrel cactus, prickly pear.
The Mediterranean-style house was set dramatically against the stark black rise of the mountains, pinned by static swords of security lights, and surrounded by stucco walls, wrought-iron gates, palm trees, ocotillo, and barrel cactus.
Once a group of big red kangaroos had bounced by, stopping to munch on some barrel cactus, undeterred by the spines.