Opuntia engelmannii var. lindheimeri

Stem segments broadly obovate to subcircular, 15-30 × 12.5-25 cm, sometimes broader than wide, to 1.5 times longer than wide. Spines (0-)1-6 per areole, evenly distributed on stem segment to absent, yellow throughout, sometimes with red or red-brown extreme bases, aging blackish, longest 12-75 mm. 2n = 66.

Flowering spring (Mar-Jun). Chihuahuan Desert, plains to woodlands and chaparral, sandy to gravelly or rocky soils; 0-1900 m; La. , N.Mex., Tex.; Mexico; South Africa (introduced).

L. D. Benson (1982) grouped all large, yellow-spined plants in the Texas region under Opuntia lindheimeri. Plants known as O. lindheimeri var. lehmannii have large, wavy stem segments that are broader than long. Opuntia lindheimeri var. tricolor (Griffiths) L. D. Benson is a morphotype with long, yellow spines to 75 mm; and O. subarmata Griffiths is a morphotype with spineless or nearly spineless stems.

Although Opuntia engelmannii var. lindheimeri is a hexaploid, like the rest of O. engelmanni, several individuals were recorded as 2n = 22, 44, and ca. 44; however, such numbers require taxon verification.

Opuntia engelmannii var. lindheimeri hybridizes with O. stricta, forming hexaploid O. ×alta Griffiths, and with O. macrorhiza Engelmann, forming pentaploid O. ×edwardsii V. E. Grant & K. A. Grant.

PADS: broadly obovate to subcircular, sometimes broader than wide, 15-30 cm long, 12.5-25 cm wide. SPINES: evenly distributed on pad to absent, clear yellow sometimes with red extreme bases, aging blackish, (0-)1-6 per areole, the largest 1.2-7.5 cm long. 2n = 66; several counts of 2n = 22, 44, ca. 44 require taxon verification. NOTES: See also parent taxon. Sandy to gravelly or rocky soils, Chihuahuan Desert, plains to woodlands and chaparral; escaped in Cochise Co.; 1000-1300 m (3300-4500 ft); Mar-Jun; LA, NM, -OK, TX; adjacent Mex.; escaped in S. Afr. REFERENCES: Pinkava, Donald J. Cactaceae. 2003. J. Ariz. - Nev. Acad. Sci. Volume 35(2).