Gard. Dict. ed. 8, Berberis no. 2. 1768.
Shrubs, deciduous, 0.4-2 m. Stems dimorphic, with long primary shoots and short axillary shoots. Bark of 2d-year stems purple or brown, glabrous. Bud-scales 1-1.5 mm, deciduous. Spines present, simple or 3 (-7) -fid. Leaves simple; petioles 0.2-0.8 (-1.3) cm. Leaf-blade oblanceolate or sometimes narrowly elliptic, 1-veined from base, 1.8-7.5 × 0.8-3.3 cm, thin and flexible, base long-attenuate, margins plane, toothed, each with 3-12 teeth 0-1 mm high tipped with bristles to 0.2-1.2 × 0.1-0.15 mm, apex rounded or rounded-obtuse; surfaces abaxially dull, smooth, adaxially dull, ± glaucous. Inflorescences racemose, lax, 3-12-flowered, 2-5.5 cm; bracteoles membranous, apex acuminate. Flowers: anther-filaments without distal pair of recurved lateral teeth. Berries red, oblong-ellipsoid, 10 mm, juicy, solid. 2n = 28.
Phenology: Flowering spring (Apr–May).
Habitat: In woods or glades, on rocky slopes and near rivers
Elevation: 100-700 m
Ala., Ga., Ill., Ind., Ky., Md., Mo., N.C., Pa., Tenn., Va., W.Va.
Berberis canadensis is susceptible to infection by Puccinia graminis.
The Cherokee Indians used scraped bark of Berberis canadensis in infusions to treat diarrhea (D. E. Moermann 1986).
"thin" is not a number.