Common barberry, Berberis vulgaris L., [BEBVU, épine-vinette commune, épine-vinette, vinetteier] Perennial, reproducing only byseed; bushy shrub 1 - 3 m (3 - 10 ft) high. stems erect; branches gray to yellowish-gray with short, sharp, slender. 3-branched spines (occasionally single or unbranched) at nearly every node; leaves in clusters or short lateral spurs along the main branches, but distinctly alternate (1 per node) on young, rapidly elongating branches; leaf blades broadest above the middle, tapering towards the base, prominently net-veined and greyish-green on the under surface, with numerous, prominent, sharp or spiny-tipped teeth; lowers bright yellow in elongated. drooping racemes from leaf axils from the ends of branches, small. each with 6 yellow sepals, 6 yellow petals. 6 stamens and 1 pistil; berries bright red, elliptical, about 1 cm (2/5 in.) long and containing 1 to 3 or rarely more seeds. Flowers in May and June; the yellow sepals and petals fall very soon afterwards, but the bright red berries often hang on all winter.

 Common barberry was introduced as an ornamental shrub, but now occurs wild along fence lines. roadsides, riverbanks, edges of woods and in wasteland throughout southern Ontario.

It is distinguished from other shrubs by its clusters of bristly toothed leaves, its 3-branched spines, its small yellow flowers in long drooping racemes, and its red berries. This plant is a very important pest because its leaves become infested with the fungus which causes stem rust on oats, barley, rye and wheat; the fungus overwinters in these leaves and spreads from them to cause early-season infections of stem rust on nearby grain crops. Eradication of this shrub is essential to help protect grain crops from the stem rust fungus.

For additional information, see Ontario Ministry of Agriculture and Food Factsheet, Common Barberry and European Buckthorn. Alternate Hosts of Cereal Rust Diseases. Agdex 110/632.

(Source: Ontario Ministry of Agriculture and Food, Publication 505, Ontario Weeds)