prairie pricklypear

O. macrorhiza is one of the shorter species of the genus, usually 7.5–12.5 cm (3.0–4.9 in) tall (but rarely over 30 cm (12 in)) and 30–180 cm (12–71 in) in diameter. O. macrorhiza grows horizontally to around 1 m (3.3 ft). forming wide clumps. Flowers are showy and bright yellow, often with red markings near the base of the petals. Fruits are narrow, red, juicy and edible.

The species prefers well-drained, sandy or gravelly soils, mostly in grassland areas. It grows at elevations of 600–2,400 m (2,000–7,900 ft). It is found throughout the Great Plains of the United States, from Texas to Minnesota, and west into the Rocky Mountain states to New Mexico, Utah, and perhaps Idaho, with sporadic populations in the Mississippi and Ohio Valleys. It is also reported from northern Mexico in the states of Chihuahua, Sonora, Coahuila, Nuevo León, Durango, Tamaulipas, and San Luís Potosí., though all Arizona and Mexican records should be considered with caution due to confusion with other similar species. The species is cultivated as an ornamental in other locations.