Shrubs , evergreen, 1-3.5 m. Stems ± dimorphic, with elongate primary and short axillary shoots. Bark of 2d-year stems gray or grayish purple, glabrous. Bud scales 2-3 mm, deciduous. Spines absent. Leaves 3-foliolate; petioles 0.8-5.4 cm. Leaflet blades thick and rigid; surfaces abaxially dull, papillose, adaxially dull, ± glaucous; terminal leaflet sessile, blade 2.3-5.8 × 0.9-2 cm, 1.6-3.1 times as long as wide; lateral leaflet blades narrowly lanceolate or narrowly elliptic, 1-veined from base, base acute or acuminate, rarely rounded-acute, margins plane, toothed or lobed, with 1-3 teeth or lobes 3-7 mm high tipped with spines to 1-2 × 0.2-0.3 mm, apex narrowly acute or acuminate. Inflorescences racemose, lax, 1-8-flowered, 0.5-3 cm; bracteoles membranous, apex acuminate. Flowers: anther filaments without distal pair of recurved lateral teeth. Berries red, sometimes glaucous, spheric, 6-11 mm, juicy, solid. Flowering winter-spring (Feb-Apr). Slopes and flats in grassland, shrubland, and sometimes open woodland; 0-2000 m; Ariz., N.Mex., Tex.; n Mexico. The illegitimate name Berberis trifoliolata Moricand var. glauca (I. M. Johnston) M. C. Johnston has been used for plants with very strongly glaucous leaves. Weakly and strongly glaucous plants are often found in the same population, however, indicating that they are not distinct varieties. Berberis trifoliolata is susceptible to infection by Puccinia graminis .

Plant: Shrubs, 1.0-2.5 m tall Leaves: trifoliolate, 3-8 cm long; leaflets narrowly lanceolate, attenuate, thick, rigid, 2-6 cm long; veins obscure; teeth of leaflet margin (0-)1-2(-3) pairs, 2.5-7 mm long including spine 1-2 mm long INFLORESCENCE: racemose, (1-)3-6-flowered, 1.0-2.5(-4) cm long; racemes 1-4 per leaf axil; pseudopedicels 5-8 mm long; bracts 1.0-2.0 mm long; bracteoles 2, opposite, appressed to calyx, or 2-4 mm below it, reddish, keeled, lanceolate, 1 mm long Flowers: sepals 9; outer sepals ovate, obtuse, 2-3 mm long; middle sepals oblanceolate, 4-5 mm long; inner sepals ovate to suborbicular, 5-7 mm long; petals oblanceolate, 3-4 mm long; filaments lacking teeth Fruit: FRUITS berries, red, pruinose, subglobose, 6-7 mm long, 4.5-5.0 mm wide, with persistent stigmas; SEEDS ellipsoid, shiny, reddish-brown, 3-5 mm long Misc: Slopes and mesas; 900-1050 m (3000-3500 ft); Mar-Apr