Common and Glossy Buckthorn was introduced to North America from Eurasia for use as an ornamental plants, as well as for its perceived habitat value. Both buckthorn species are capable of aggressive growth habits in natural areas. Glossy buckthorn has the capacity to replace entire wetland plant communities, whereas common buckthorn grows aggressively in areas with drier soils. Neither plant supports the diversity of birds, butterflies, and other wild creatures once sustained by the native plants.
Although seedlings of both buckthorns invade stable habitats, they grow most successfully where there is ample light and exposed soil such as when the land is disturbed by building, changes in drainage, tree harvesting and grazing in woodlots. Both species of buckthorn have long growing seasons and rapid growth rates, and will sprout vigorously after being cut. Both species leaf out prior to most native deciduous plants, and can retain their leaves well into autumn allowing them to form dense, even-aged thickets that shade out native plants. This can cause habitat degradation, shade out rare species, and give rise to declines in native species diversity. Both species have become widespread in North America and Bay County. Dispersal is accelerated by the birds and mammals that feed on the fruit of these species.
Common buckthorn is a deciduous shrub or small tree that grows up to 20 feet in height. Dull green leaves are oval, edged with fine teeth, and one to twoinches long. The leaves have several pairs of distinct veins that are curved toward the leaf tip. Leaf arrangement on the stem is alternate to nearly opposite. Twigs may be tipped with sharp, stout thorns. Small clusters of fragrant greenish-yellow flowers, each with four petals, grow from among the leaves.
Glossy buckthorn is a deciduous shrub or small tree, similar to common buckthorn though it can readily be distinguished from common buckthorn by several factors. Glossy buckthorn has similarly shaped leaves, but they are glossy or shiny and lack teeth on their margins. Flowers are also similar, but have five petals. Plants of both species reach seed-bearing age quickly, and both produced rupes (berries).