Berberis nervosa Pursh var. mendocinensis Roof; Mahonia nervosa (Pursh) Nuttall; M. nervosa var. mendocinensis (Roof) Roof

Shrubs , evergreen, 0.1-0.8(-2) m. Stems monomorphic, without short axillary shoots. Bark of 2d-year stems brown or yellow-brown, glabrous. Bud scales (13-)20-44 mm, persistent. Spines absent. Leaves 9-21-foliolate; petioles 2-11 cm. Leaflet blades thin and ± flexible; surfaces abaxially rather dull, smooth, adaxially dull, somewhat glaucous; terminal leaflet stalked, blade 2.9-8.4 × 1.2-4.8 cm, 1.8-3.2 times as long as wide; lateral leaflet blades lance-ovate to ovate, 4-6-veined from base, base rounded to cordate, margins plane, toothed, each with 6-13 teeth 1-2(-3) mm tipped with spines to 1-2.4 × 0.1-0.2 mm, apex acute or broadly acuminate. Inflorescences racemose, dense, 30-70-flowered, 6-17 cm; bracteoles membranous, apex acute, obtuse, or rounded. Flowers: anther filaments without distal pair of recurved lateral teeth. Berries blue, glaucous, oblong-ovoid or globose, 8-11 mm, juicy, solid. 2 n = 56.

Flowering winter-spring (Mar-Jun). Open or shaded woods, often in rocky areas; 0-1800 m; B.C.; Calif., Idaho, Oreg., Wash.

Plants of Berberis nervosa are usually very low (commonly 0.1-0.3 m), but occasional plants may be considerably taller (to 2 m). One such population from north of Westport, California, has been separated as B . nervosa var. mendocinensis . Similar populations occur sporadically throughout the range of B . nervosa , so the form should not be recognized taxonomically.

Berberis nervosa is resistant to infection by Puccinia graminis .

The Skagit tribe used Berberis nervosa medicinally in a root preparation to treat venereal disease (D. E. Moermann 1986).