Taxonomy and Synonyms
The name Opuntia setispina Wooton is most commonly treated as a synonym for:- Cylindropuntia whipplei var. setispina (Wooton) Peebles
- Or simply recognized as part of the broader species Cylindropuntia whipplei (Engelm. ex B.D. Jacks.) F.M. Knuth.
This reclassification reflects modern phylogenetic understanding, which has separated the "cholla" cacti (now Cylindropuntia) from the "prickly pear" cacti (Opuntia sensu stricto) based on differences in stem structure, spine characteristics, and floral morphology. The epithet "setispina" refers to the bristly or stiff-haired spines often found on this particular variety.
Description (of Cylindropuntia whipplei var. setispina)
As a variety of Cylindropuntia whipplei (commonly known as Whipple Cholla or Rat-tail Cholla), Opuntia setispina refers to a plant characterized by:- Growth Habit: Typically a low-growing, sprawling, or erect shrub, often forming dense clumps. It can reach heights of 1 to 3 feet (0.3 to 1 meter).
- Stems: Composed of cylindrical, segmented joints that are often easily detached. These segments are green to grayish-green and bear prominent tubercles.
- Spines: Numerous, usually barbed, and arranged in clusters (areoles) along the stem segments. The specific characteristic implied by "setispina" suggests particularly bristly or fine, hair-like spines in addition to the larger, more rigid ones. These spines can be white, yellow, or reddish-brown.
- Glochids: Small, barbed bristles located in the areoles, which can be irritating upon contact.
- Flowers: Solitary or in small clusters, typically appearing in late spring to early summer. They are usually yellowish-green, sometimes with reddish tinges, and measure about 1 to 1.5 inches (2.5 to 3.8 cm) in diameter.
- Fruit: Fleshy, greenish-yellow, and tuberculate (bumpy) when mature. They are often sterile, meaning they do not produce viable seeds, and may persist on the plant for extended periods.
Habitat and Distribution
The plants referred to by Opuntia setispina (i.e., Cylindropuntia whipplei var. setispina or Cylindropuntia whipplei) are native to the arid and semi-arid regions of the southwestern United States and parts of northern Mexico.- Distribution: Found across states such as Arizona, New Mexico, Utah, Colorado, Nevada, and California.
- Habitat: Typically grows in desert grasslands, shrublands, piñon-juniper woodlands, and sandy or gravelly soils at elevations ranging from low desert floors to higher montane areas. It is well-adapted to drought conditions and poor soils.