Stems 14--35 cm. Leaves: blade 5--45 ´ 0.4--0.9 cm. Flowers: pedicels 1--2 cm, glabrous; sepals 5--8 mm, glabrous; petals bright blue, 0.7--1 cm. Flowering spring--summer, fall (Apr--Aug, Oct). Moist canyons and stream banks; Ariz., N.Mex. The two varieties intergrade; the only absolute difference between them is sepal pubescence. Tradescantia occidentalis var. scopulorum evidently was defined more broadly by W. C. Martin and C. R. Hutchins (1980), so the distribution I have shown for New Mexico could be too wide. A broader circumscription of this variety has also been used by others (C. Sinclair 1967; M. Bolick 1986), but I have not accepted these records. Most specimens of Tradescantia occidentalis from Arkansas and Louisiana have an apical tuft of eglandular hairs on the sepals, a character acquired through introgression with T. ohiensis (E. Anderson and R. E. Woodson Jr. 1935).
Tradescantia occidentalis var. melanthera has been described for plants from Arkansas, Louisiana, eastern Texas and eastern Oklahoma that have dark anther connectives (D. T. MacRoberts 1977). I have not been able to recognize this character in dried specimens with any consistency.
LEAVES: blades 5-50 cm long, 0.4-0.9 cm wide. FLOWERS: pedicels 1-2.5 cm long, glabrous; sepals 5-8.5(-10) mm long, 2.5-4.4 mm wide, glabrous; petals 7-14 mm long, 8-13 mm wide, bright blue. NOTES: See also parent taxon. Riparian habitats, mesquite and oak woodlands to pine-oak forests; Gila, Graham, Pima, Pinal cos.; 800-1900 m (2600-6300 ft); Feb-Jun; AZ, NM; n Mex. REFERENCES: Puente, Raul, and Robert B. Faden. 2001. Commelinaceae. J. Ariz. - Nev. Acad. Sci. Volume 33(1).