Gibbes, Proceedings of the Elliott Society of Natural History of Charleston, South Carolina 1: 273, 1859
In 1919 Britton and Rose described Opuntia macrarthra as long overlooked; that is still the case today. This species is found along the coast of South Carolina and its islands. Britton and Rose describe the taxon as: “Stems prostrate or ascending; joints narrowly oblong to obovate, 12 to 35 cm. long, thick, pale green, somewhat shining; leaves subulate, 10 mm. long, green, sometimes with purplish tips; areoles large, 2 to 3 cm. apart, filled with brown wool; spines wanting, or sometimes 1, up to 2.5 cm. long; glochids when present yellow; flowers not known; fruit narrowly obovoid, red, fleshy, 4 to 6 cm. long” O. macrarthra is similar to O. bentonii in overall appearance, perhaps they are related. See the original description.