Shrubs , evergreen, 1-2 m. Stems ± dimorphic, with elongate primary and short or somewhat elongate axillary shoots. Bark of 2d-year stems purple, glabrous. Bud scales 1.5-4 mm, deciduous. Spines absent. Leaves 5-9-foliolate (basal pair of leaflets sometimes reduced to bristles); petioles 0.1-0.5 cm. Leaflet blades thin or thick and rigid; surfaces abaxially dull, papillose, adaxially dull, somewhat glaucous; terminal leaflet stalked (sessile in a few leaves), blades 1.8-3.5 × 0.7-1.7 cm, 1.3-4.7 times as long as wide; lateral leaflets oblong to elliptic or lanceolate, 1-veined from base, base truncate to obtuse, rarely acute, margins plane or undulate, toothed, each with 3-8 teeth 0.5-2 mm high tipped with spines to 0.6-1.2 × 0.1-0.2 mm, apex rounded to acuminate. Inflorescences racemose, lax, 2-6-flowered, 4-6 cm; bracteoles leathery, apex spinose-acuminate, sometimes with proximal bracteoles as described, distal membranous and acuminate. Flowers: anther filaments with distal pair of recurved lateral teeth. Berries white or red and somewhat glaucous, spheric, 9-16 mm, dry or juicy, hollow. Flowering winter-spring (Feb-Apr). Limestone ridges and canyons; 150-600 m; Tex. Berberis swaseyi is endemic to the Edwards Plateau. According to M. C. Johnston (pers. comm.), B . swaseyi and B . trifoliolata hybridize in central Texas. Berberis swaseyi is susceptible to infection by Puccinia graminis .