Rep. (Annual) Missouri Bot. Gard. 21: 170, plate 25. 1910.
Shrubs, low, spreading, to 2 m. Stem segments strongly interconnected, blue-green, flattened, obovate to ovate or circular, 15–25 × 10–20 cm, glaucous, low tuberculate, glabrous; areoles 5–7 per diagonal row across midstem segment, often fan-shaped with small circular extensions at base, 2.5–5(–10) mm diam., base surrounded by glabrous yellow lip; wool white, aging blackish. Spines absent or vestigial, yellow. Glochids few, scattered, poorly developed, yellow, aging gray to blackish, to 1.5 mm, covered by white, cottony wool. Flowers: inner tepals brilliant yellow throughout, fading orange to red, 25–30 mm; filaments white to green; anthers yellow; style white; stigma lobes bright light green. Fruits pink- to red-purple with red pulp, pyriform, 30 × 25 mm, fleshy, glabrous, spineless; areoles 18–25, usually crowded near apex, long, white woolly. Seeds tan, subcircular, 2 mm diam.; girdle broad, projecting 0.5 mm. 2n = 22.
Phenology: Flowering spring (May–Jun).
Introduced; Ariz., Tex., Mexico.
Opuntia ellisiana is only known from cultivation in the United States; the type is from a cultivated plant growing in Corpus Christi, Texas.
Opuntia ellisiana has been confused with O. ficus-indica; their fruits are readily separable in the number and distribution of areoles and fruit size.