Griffiths, Annual Report of the Missouri Botanical Garden 20: 93, 1909
Holotype; Isotype; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Painting (watercolor over photograph, Krieger and Griffith, 1915, Smithsonian Institution Archive); Photograph (D Griffiths, ca. 1910); Photograph (D Griffiths, ca. 1910); Photograph (Annual Report of the Missouri Botanical Garden, 20: 1909)
What is Opuntia arizonica?
Opuntia arizonica is a seldom-reported species of prickly pear cactus. It is not rare but is usually lumped into O. engelmannii as a spiny and small specimen and thus is an unnoticed Opuntia. It has been found near Congress, AZ in Tucson, AZ, in central NM, and in the greater El Paso region.
This prickly pear cactus resembles O. engelmannii but is spinier. Additionally this particular Opuntia is decidedly smaller than the large O. engelmannii. O. arizonica may be nearly prostrate or may ascend to 30-40 cm tall or a bit more. Plants my be 50 cm across, or they may sprawl to 1 m. Cladodes are typically 25-30 cm across and subcircular. Areoles become relatively large (1.5-3 cm across) with age and they darken. Sometimes the tissue of an areole my proliferate creating a bump in the center. There are (2)3-4(6) stout spines per areole on this Opuntia; the longest may be 2.5 to 5 cm long. Glochids may be scattered throughout the areoles, but are most numerous in the upper portion.
Flowers are average in size and yellow. The fruit of this prickly pear is reported to be subglobose, but we have observed egg-shaped fruit. O. arizonica may be the same taxon as O. sp nova aff engelmannii. See the original citation. Ploidy is not known.