PLANT: Shrubs to 2 m tall. STEMS: erect, greenbrown to gray, tomentose to glabrous at maturity. LEAVES: evergreen, opposite; petioles 1-3 mm long; blades elliptic to obovate, pinnately veined, 0.6-1.9 cm long, 0.5-1 cm wide, gray-green, pilose to glabrate; margins entire to spinose-dentate. INFLORESCENCE: axillary, 3-10 flowers per cluster, usually not exceeding the leaves. FLOWERS: often white, sometimes blue to purple. FRUITS: 3-5 mm wide. NOTES: Desert mountains, chaparral: Coconino, Cochise, Gila, Graham, La Paz, Mohave, Pima, Mohave,Yavapai cos.; 900-2100m (3000-6900ft); Mar-May. CA, NM, NV, UT, sw TX; n Mex. McVaugh (1998) presents evidence that Ceanothus greggii A. Gray cannot be recognized as it is a later heterotypic synonym of C. pauciflorus DeCandolle. Furthermore AZ populations of this complex apparently all belong to C. vestitus. Some authorities list Ceanothus greggii var. greggii (now correctly referred to as C. pauciflorus) and C. greggii var. perplexans (now correctly named C. perplexans) as occurring in AZ. Ceanothus pauciflorus occurs broadly in n Mex. from Son., Chih., Coah. and N. L. s to Tamps. and S. L. P. It can be recognized by convex or flat upper leaf surfaces, tomentulose lower leaf surfaces, and thick to revolute margins. Typical Ceanothus perplexans is restricted to the Peninsular Ranges of CA s to Baja C., Mex. and can be recognized by broadly obovate to orbicular leaf blades that are usually flat with 5-11 weakly spinulose teeth on the margins. Recognition of either C. pauciflorus or C. perplexans in AZ or documentation of possible introgression with C. vestitus must await a thorough revision of this entire group. REFERENCES: Kyle Christie, Michael Currie, Laura Smith Davis, Mar-Elise Hill, Suzanne Neal, and Tina Ayers, 2006 Vascular Plants of Arizona: Rhamnaceae. CANOTIA 2(1): 23-46.