Habitat: Glossy buckthorn can be found in either the floodplain or emergent plant community. It invades moist wetlands and disturbed areas like swamps, bogs, fens, and wet meadows; however, is not confined to wet soils and can also invade upland sites such as old fields and roadsides.
Description: Glossy buckthorn is a tall shrub or small tree (2-7 m; 6-21ft) which is often many-stemmed. The leaves are arranged alternately on the stem, 3 to 7 cm long and 2.5 to 4 cm wide, with smooth edges and a glossy upper surface. The flowers are greenish-white, star-shaped, five-petaled, 3-5mm wide and occur singly or in small clusters where leaves meet the stem and bloom from May to June. Glossy buckthorn produces berries that are 0.5 cm across which turn from green or red to black as they ripen and are non-edible. The bark of younger trees is smooth, with small dash-like markings, becoming rougher with age. Inner bark is bright yellow and the heartwood is orange.
Origin and Range: Glossy buckthorn is native to Europe, North Africa and Central Asia. It is not native to North America and was introduced to this country as an ornamental species in the early 1800s. In Canada, it has now spread from the Maritime Provinces to the prairies. In New Brunswick; it is spreading rapidly and is now very common in many areas along the Miramichi and Saint John River valleys.
Annual Cycle: Glossy buckthorn is a perennial that reproduces only by seed. It flowers after the leaves expand, from May to June. The fruit ripen from July to August. It is important to note that at any given time there can be flowers, partially ripened fruits and fully ripened fruits present on the same plant.
Look Alikes: Glossy buckthorn may be confused with Common buckthorn (Rhamnus cathartica L.). However, glossy buckthorn can be readily distinguished from common buckthorn by several obvious characters. Common buckthorn has similarly shaped leaves, but they are dull green (not glossy), arranged oppositely on the stem, and are edged with fine teeth. Common buckthorn also has a short, sharp spike-like thorn at the tip of its branches, which is absent in glossy buckthorn.
Impacts: Glossy buckthorn is considered to be the most troublesome invasive plant in New Brunswick. Once established, glossy buckthorn can spread aggressively, forming dense thickets that shade out native shrubs and herbs, often completely eliminating them. The dense buckthorn seedlings also inhibit the growth of native shrub and tree seedlings.