small logoThe Friends of the Wild Flower Garden, Inc.

Trees and Shrubs of the Eloise Butler Wildflower Garden

The oldest public wildflower garden in the United States

Glossy Buckthorn

Common Name
Glossy Buckthorn (European Alder Buckthorn)

 

Scientific Name
Frangula alnus Mill.

 

Plant Family
Buckthorn (Rhamnaceae)

Garden Location
Woodland

 

Prime Season
Spring flowering, early Autumn Ripe Fruit

 

 

Glossy Buckthorn is an erect perennial shrub introduced from Europe that has naturalized and is invasive. While usually found as a multi-stemmed shrub, older specimens can develop into a single trunk tree that will reach 20 feet in height.

The bark is a smooth grayish-brown with some raised whitish lenticels that will become shallow fissures on larger older stems. Sapwood is yellow and heartwood is orange.

Twigs are slender, gray-brown to reddish-brown with some fine gray hair and lacking thorns. Buds are tan.

Leaves are alternate, simple, elliptical to oblong in shape, 2 to 4 inches long. Margins are smooth, sometimes wavy, the upper surface a shiny dark green, pale underside, and with a short stalk with fine hair. Leaf veins have one central vein with 5 to 10 pair of parallel lateral veins, which curve toward the tip at the leaf margins. Leaves are a little broader near the apex which has a slight point.

The Inflorescence is a small group (an umbel) of 1 to 6 flowers rising from the leaf axils in late spring after the leaves have opened. The umbel is not stalked.

Flowers: Individual flowers are very small, bell shaped with 5 small pale yellow-green petals and 5 larger yellow-green sepals, both with pointed lobes. The calyx is hemispheric in shape on a long stalk. While the flowers are perfect they require insect pollination. There are five stamens placed with the petals and a single style leading to a multi-celled ovary.

Fruit: Flowers mature to a 1/4 inch juicy drupe that turns from green to reddish and then to black, each containing 1 to 2 (usually 2) yellowish-brown seeds (nutlets), 5 to 6 mm long, that are ovoid in shape but flattened and dimpled, with a ridge line on one of the flattened sides, and with a beak at one end. It is not uncommon to find fruit in all three stages of coloration on the same branch and sometimes even with flowers still present.

 

Habitat: Glossy Buckthorn grows in many moist environments from swamps to meadows to wood edges. It is shade tolerant. It forms thickets and the seeds can be  widely dispersed by  birds as the drupe produces a laxative effect on birds, but only larger birds can probably handle the larger nutlets. Cut stems must be treated with a brush or stump killer to prevent regeneration.

Names: This plant was formerly classified by Linnaeus in the genus Rhamnus as Rhamnus frangula, but is now in the genus Frangula. This was primarily due to Rhamnus having flowers with 4-parted corollas and separate sexes, while Frangula has flowers with 5-parted corollas and perfect flowers. The name Frangula, means brittle wood while the species, alnus, refers to this plants tendency to grow together with some of the alders. The author name for the plant classification, "Mill." refers to Philip Miller, Scottish botanist (1691-1771) who was chief gardener at the Chelsea Physic Garden and wrote "The Gardener's Dictionary".

Comparisons: Glossy Buckthorn is most easily confused with the native Alder-leaf Buckthorn, Rhamnus alnifolia, but there the leaves have serrated edges and the flowers are 4-parted. Another species is Common Buckthorn, Rhamnus cathartica, whose leaves are also serrate, but not shiny, and the black drupes  develop all at one time and do not go through a red stage, the flower (4-parted) clusters are much more dense and the twigs also have thorns. All three retain their green leaves late into autumn when most deciduous species have shed theirs.

See bottom of page for notes on the Garden's planting history, distribution in Minnesota and North America, lore and other references.

flower detail Glossy Buckthorn flowering  stem

Above: 1st photo - The flower has 5 sepals much larger than the 5 petals. Stamens and their dark anthers rest against the small petals. In the center is the greenish style with divided blunt tips. 2nd photo - Clusters appear all along a fruiting branch.

Glossy Buckthorn Flower Glossy Buckthorn mature fruit

Above: 1st photo - The pale yellow-green 5-part flowers which spring from a leaf axil in a cluster. The calyx is hemispheric shaped (bell shape in flower) with the lower part of the sepal lobes green and upper part yellowish. 2nd photo - The mature fruit is a glossy black 1/4 inch drupe, which is first green, then red before turning black.

Below: 1st photo - Fruit in the red stage before turning black. 2nd photo - the flattened nutlets, usually 2 to each drupe, about 5 to 6 mm long.

Glossy Buckthorn red fruit seeds

Below: 1st photo - A small plant of Glossy Buckthorn. 2nd photo - It is common to find drupes in all color stages on a branch.

Glossy Buckthorn shurb Glossy Buckthorn berries

Below: 1st photo - The leaf has smooth, but sometimes wavy margins and 5 to 10 pair of lateral veins that curve toward the pointed tip. 2nd photo - Older larger stems are grayish-brown with raised lenticels. 3rd photo - Young stems are gray-brown to reddish-brown with conspicuous light colored lenticels.

Glossy Buckthorn leaf Glossy Buckthorn bark Glossy Buckthorn twig

Notes:

Notes: Eloise Butler listed Glossy Buckthorn on her list of plants indigenous to the Garden. It has been on every census since. Glossy Buckthorn is found in the U.S. in the NE quadrant from Minnesota eastward, south as far as Tennessee and West Virginia plus a few western states. In Canada it is found from Saskatchewan eastward except Labrador and Newfoundland. It is listed as a prohibited or restricted noxious weed in five states, including Minnesota. Within Minnesota it is known in the metro area counties plus Wabasha, Houston and St. Louis. It is native to Europe, Northern Africa and Asia and it was first collected in North America in 1898 in London, Ontario. It has spread via the nursery trade which provided it as an ornamental, similar to the other invasive Common Buckthorn - Rhamnus cathartica.

Like the latter species, Glossy Buckthorn is kept under control by the Garden Staff.

References and site links

References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.

©2013

072416