Trees or shrubs, densely branched, 0.5-3 m. Stem segments green, sometimes purple tinged, 6-10.5 × 0.5-1.3 cm; tubercles narrowly elongate, appearing as wrinkles when dry, 1-2 cm; areoles circular, 2-3 mm in diam.; wool tan to brown, aging gray to black. Spines 0-2(-3) per areole, sparsely distributed along stem, usually deflexed, pale yellow or red-brown aging black, stout, the longest 0.8-3.5(-5) cm; sheaths loose fitting, yellowish brown. Glochids in adaxial tuft and marginal, encircling areole, pale yellow. Flowers: inner tepals green- or orange-bronze, spatulate, 17-20 mm, apiculate; filaments dark green-bronze; anthers yellow; style whitish basally to light orange apically; stigma lobes very pale green. Fruits green, becoming yellowish apically, sometimes tinged red to purplish at areoles, commonly sterile, then narrow, tuberculate, to 2.5 cm, fertile ones stipitate, obconic, 20-50 × 15-35 mm, fleshy, becoming smooth, spineless; umbilicus 3-4 mm deep; areoles 15-17(-34). Seeds pale yellow, angularly circular to oblong, thick, 3-5 mm diam., lumpy; girdle smooth, broad, not protruding. 2n = 66. Flowering spring (Apr-Jun). Sonoran Desert flats, bajadas, desert scrub; 300-1000 m; Ariz.; Mexico (Sonora). Cylindropuntia arbuscula forms hybrids with C. leptocaulis in south-central Arizona; those hybrids have narrow, obscurely tuberculate stems and reddish fruits nearly the size of those of C. arbuscula and chromosome number of 2n = 55. Hybrids between C. arbuscula and C. spinosior [= C . ×neoarbuscula (Griffiths) F. M. Knuth] have large green fruits, which often split open, and on stem segments distal areoles that usually bear three or four spines to 2.5 cm. Hybrids between C. arbuscula and C. versicolor [= C . ×vivipara (Rose) F. M. Knuth] have large green fruits, which often split open, and distal stem segment areoles that bear one or two spines to 1.5 cm.

Plant: Tree or shrub, much branched, 0.5-3 m tall; STEM segments green, sometimes purple-tinged, 6-10.5 cm long, 0.5-1.3 cm in diam.; tubercles obscure, narrowly elongate appearing as wrinkles when dry, 1-2 cm long. AREOLES tan- to brown-felty, aging gray to black, circular, 2-3 mm in diam Leaves: SPINES 0-2(-3), sparsely distributed along stem, pale yellow to red-brown aging black, stout, usually deflexed, the longest 0.8-3.5(-5) cm long; sheaths loose-fitting, yellowish brown. GLOCHIDS pale yellow, in an apical tuft with a few marginal ones, encircling areole Flowers: inner tepals dark bronze to orange bronze, spatulate, apiculate, 1.7-2 cm long; filaments dark green-bronze, the anthers yellow; style whitish basally to light orange apically; stigmas very pale green Fruit: green becoming yellowish apically, sometimes purplish at areoles, obconic-stipitate, commonly sterile, narrow and tuberculate to 2.5 cm long, the fertile ones obconic-stipitate, becoming smooth, spineless, fleshy, 2.5-5 cm long, 1.5-3.5 cm in diam., the umbilicus 3-4 mm deep; areoles 15-17(-34). SEEDS 3-5 mm in diam., pale yellow, angularly circular to oblong, thick, lumpy, the girdle smooth, not protruding Misc: Desert flats and bajadas, desertscrub; 350-1000 m (1000-3300 ft); Apr-Jun REFERENCES: Pinkava, Donald J. 1999. Cactaceae. Ariz. – Nev. Acad. Sci. 32(1).