Opuntiaangustata is a poorly understood or documented prickly pear reported from northwestern Arizona and adjacent portions of Nevada and California. The photos presented here represent our concept of this cactus. O.angustata is larger and woodier/stiffer than O.phaeacantha but is smaller than O. engelmannii to which it is related. Spines are often long and chalky white. Britton and Rose reported that the true type specimen is from the bottoms of the Bill Williams River in AZ. Engelmann and Bigelow described a plant that had narrow cladodes. O.angustata and O.riparia are similar and may in fact represent the same taxon. O.riparia occurs further south (near Tucson, AZ and below). Also, we interpret O.angustata to be the same as O.magnarenesis described by Griffiths from Owens, AZ (near Wikieup, AZ), which does not have especially narrow cladodes. See the original citation of O.angustata. See the original citation of O. magnarenensis.