Water chestnut (Trapa natans)
Photo credit: © Anne Vorstenbosch/Flickr

Glossy Buckthorn

(Rhamnus frangula)

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Species at a Glance

Also known as European alder or smooth buckthorn, glossy buckthorn is a large shrub to small tree that can grow as high as 5.5 m (18 ft) but is usually closer to 3-3.7 m (10-12 ft) tall, 2.4-3.7 m (8-12 ft) wide, and 25 cm (9.8 in) in diameter.

Identification

Leaves: Thin, glossy, dark green, oblong leaves alternate on the stem. Size is 2.5-8 cm (1-3.1 in) in length and the leaf stalk is one-third the length of the blade. The upper leaf surface is shiny, while the lower surface can be hairy or smooth, and leaf margins are smooth instead of serrated. A diagnostic characteristic of buckthorns, which is shared only with dogwoods, is the lateral veins that curve to follow the leaf margins as they approach the edges. Buckthorns leaf out early in the spring and retain their leaves (which do not change color) into late fall.

 

Flowers: Small flowers with five petals are arranged in creamy green clusters that bloom in May or early June.

 

Fruits/Seeds: Small berries, about 1 cm (0.4 in) in diameter, are arranged in large clusters. Fruit is red-brown in color, changing to black when it ripens and falls in July through September. Each fruit contains 2-4 smooth, ungrooved seeds.

 

Stems/Roots: Warty-looking or bumpy branches have naked hairy buds. A cut branch reveals yellow sapwood and a pink to orange colored heartwood.

Similar Species

This plant is often confused with other buckthorn species, including the invasive common buckthorn (Rhamnus cathartica), the native alder buckthorn (Rhamnus alnifolia), and the lance-leafed buckthorn (Rhamnus lanceolata). Unlike glossy buckthorn, common buckthorn flowers have four petals, twigs are tipped with short spines, and leaves are smooth on both surfaces, with serrated edges. Native buckthorns are also much smaller, with alder buckthorn reaching only 0.9 m (3 ft) high and lance-leafed buckthorn reaching 1.8 m (6 ft) high.

Habitat

Aggressively 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.

Spread

Glossy buckthorn propagates mainly by seed, so dispersal occurs as the fruits are consumed by birds and mice and are distributed over long distances.

Distribution

Native to Eurasia, it was introduced as an ornamental shrub because of its hardiness and ability to thrive in varying light and soil conditions. It is now widespread in many areas and can be found throughout Pennsylvania, where it is still cultivated under the alias ‘tallhedge’.

 

Note: Distribution data for this species may have changed since the publication of Pennsylvania's Field Guide to Aquatic Invasive Species (Second Edition 2015), the source of information for this description.

Environmental Impacts

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.

Video
Note

Information for this species profile comes from Pennsylvania's Field Guide to Aquatic Invasive Species (Second Edition 2015)