Description from Flora of China
Cactus dillenii Ker Gawler, Bot. Reg. 3: t. 255. 1818; Opuntia stricta (Haworth) Haworth var. dillenii (Ker Gawler) L. Benson.
Shrubs sprawling or erect, 1-3 m tall. Trunk absent or short. Larger, terminal joints green to gray-green, obovate or elliptic-obovate to suborbicular, 10-35(-40) × 7.5-20(-25) cm. Areoles 2-9 mm in diam. Spines 1-12(-20) per areole on most areoles, spreading, yellow, ± brown banded or mottled, subulate, straight or curved, 1.2-4(-6) cm, basally flattened; glochids yellow. Leaves subulate, 4.5-6 mm, deciduous. Flowers 5-9 cm in diam. Sepaloids greenish with yellow margin, broadly deltoid-obovate to obovate, 10-25 × 6-12 mm, margin entire or slightly crisped, apex mucronate. Petaloids spreading, bright yellow, obovate or cuneate-obovate, 25-30 × 12-20 mm, margin entire or slightly undulate, apex rounded, truncate, or emarginate. Filaments yellow, ca. 12 mm; anthers yellow, ca. 1.5 mm. Style yellow or yellowish, 12-20 mm; stigmas 5, pale green, ca. 4.5 mm. Fruit purple, turbinate to obovoid, 4-6 × 2.5-3(-4) cm, fleshy at maturity, umbilicus deep. Seeds light tan, irregularly orbicular, 4-5 × 4-4.5 mm. Fl. Jun-Oct(-Dec).
This species was first recorded in China in 1702.
Thickets, rocks, sandy soils, also cultivated as a hedge; near sea level. S Guangdong, S Guangxi, Hainan [native to the Caribbean region; widely introduced and naturalized in tropical regions].