Sideroxylon lanuginosum subsp. rigidum

Leaves: petiole hairy to glabrate, hairs white to gray; blade dull adaxially, 15-50 mm, abaxial surface densely to sparsely villous or glabrate, hairs white to gray.

Flowering Jun-Jul. Upland forests, woodlands, scrublands; 400-2000 m; Ariz., N.Mex., Okla., Tex.; Mexico (Coahuila, Nuevo León, Tamaulipas).

Subspecies rigidum occurs in the southwestern portion of the range and has leaf indument ranging from tomentose to glabrate. Variation patterns are especially complex in southern and western Texas and in northern Mexico.

NOTES: See also parent taxon. In thickets along stream bottoms or washes in oak or mesquite woodlands: Cochise, Pima, Santa Cruz cos.; 900-1500 m (3000-5000 ft); May-Jul (fr. Sep-Oct); se and midwest U.S. to s AZ and n Mex. Pennington recognizes 3 subspp., of which only subsp. rigidum (A. Gray) Pennington occurs in AZ, differing from others in having leaves less than 5 cm long. REFERENCES: Landrum Leslie R. 1992. Sapotaceae. Ariz.-Nev. Acad. Sci. 26(1)2.