3. Berberis vulgaris L. (common barberry)

Pl. 302 d, e; Map 1271

Shrubs 100–300 cm high. Second-year twigs with the bark gray; spines simple or 3-branched. Petioles 2–8 mm long. Leaf blades obovate to oblanceolate or almost elliptical, 2–5 cm long, 0.9–2.3 cm wide, short- to long-attenuate at the base, rounded or bluntly pointed at the tip, each margin with (8–)16–30 spine- or bristle-tipped teeth. Inflorescences lax racemes 2–6 cm long, with 10–20 flowers. Fruits 10–11 mm long, red or purple, ellipsoidal. 2n=28. May–June.

Introduced, uncommon in the eastern half of the state (native of Europe; widely naturalized across temperate North America). Mesic to dry upland forests, often in rocky places; also dry pastures and roadsides.

During the eighteenth and nineteenth centuries, B. vulgaris was very commonly cultivated in North America for thorn hedges and as a source of jam, jelly, flavoring, beverage, medicine, and yellow dye. It sometimes escaped from cultivation and became widely naturalized in portions of the United States and Canada, including Missouri. Prior to 1920, as an important winter host of black stem rust of wheat, B. vulgaris was responsible for heavy losses to grain growers. However, it has been the subject of a vigorous eradication program by the federal and state governments, and it is now seldom seen in Missouri.