Arizona Thistles (Cirsium arizonicum) have red flowers to attract hummingbirds and numerous, wickedly-sharp spines to repel browsing animals.

Arizona Thistles bloom from May to October and are often found growing along roadsides. They are most common above 5000 feet (1524 m) in the mountains around Tucson, but a few stragglers can be found growing at lower elevations in canyons with mountain runoff.