AppearanceBerberis vulgaris is a deciduous shrub that can reach 13 ft. (4 m) in height. Arching branches which come into contact with the soil can produce new plants.Foliage The leaves are oval, 0.75-2 in. (2-5 cm) long, 0.25-0.75 in. (1-2 cm) wide, serrate and occur in clusters of 2-5. Each cluster of leaves is subtended by a short, three-branched spine. Flowers Flowering occurs in May to June, when small, yellow, less than 0.25 in. (6 mm) wide flowers develop in dangling racemes. The flowers have an unpleasant odor. Fruit Berries are red ellipsoids which are less than 0.3 in. (10 mm) in length and contain 1-3 small black seeds. The fruit is dispersed by birds and other wildlife.Ecological ThreatBerberis vulgaris is shade tolerant which allows it to easily invade woodlands. It is also an alternate host for wheat rust (Puccinia graminis) which makes the control and removal of this invasive shrub of primary importance. It was introduced to America during the 17th century. Fruit of Berberis vulgaris was used to make jam, the flowers for dye and the thorny shrub provided effective livestock fencing. It is native to central and southern Europe.