Frangula alnus, syn. Rhamnus frangula, the Alder Buckthorn, is a tall deciduous

Deciduous

Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...

 shrub in the family Rhamnaceae

Rhamnaceae

Rhamnaceae, the Buckthorn family, is a large family of flowering plants, mostly trees, shrubs and some vines.The family contains 50-60 genera and approximately 870-900 species. The Rhamnaceae have a worldwide distribution, but are more common in the subtropical and tropical regions...

. It is native to Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, northernmost Africa

Africa

Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

, and western Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

, from Ireland

Ireland

Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

 and Great Britain

Great Britain

Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

 north to 68°N in Scandinavia

Scandinavia

Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...

, east to central Siberia

Siberia

Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...

 and Xinjiang

Xinjiang

Xinjiang is an autonomous region of the People's Republic of China. It is the largest Chinese administrative division and spans over 1.6 million km2...

 in western China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

, and south to northern Morocco

Morocco

Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...

, Turkey

Turkey

Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...

, and the Alborz

Alborz

Alborz , also written as Alburz, Elburz or Elborz, is a mountain range in northern Iran stretching from the borders of Azerbaijan and Armenia in the northwest to the southern end of the Caspian Sea, and ending in the east at the borders of Turkmenistan and Afghanistan...

 and Caucasus Mountains

Caucasus Mountains

The Caucasus Mountains is a mountain system in Eurasia between the Black Sea and the Caspian Sea in the Caucasus region .The Caucasus Mountains includes:* the Greater Caucasus Mountain Range and* the Lesser Caucasus Mountains....

; in the northwest of its range (Ireland, Scotland), it is rare and scattered. It is also introduced and naturalised

Naturalisation (biology)

In biology, naturalisation is any process by which a non-native organism spreads into the wild and its reproduction is sufficient to maintain its population. Such populations are said to be naturalised....

 in eastern North America.

Taxonomy and naming

Alder Buckthorn was first formally described by Linnaeus

Carolus Linnaeus

Carl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology...

 in 1753 as Rhamnus frangula. It was subsequently separated by Philip Miller

Philip Miller

Philip Miller FRS was a Scottish botanist.Miller was chief gardener at the Chelsea Physic Garden from 1722 until he was pressured to retire shortly before his death...

 in 1768 into the genus Frangula on the basis of its hermaphrodite flowers with a five-parted corolla (dioecious, and four-parted in Rhamnus); this restored the treatment of pre-Linnaean authors, notably Tournefort

Joseph Pitton de Tournefort

Joseph Pitton de Tournefort was a French botanist, notable as the first to make a clear definition of the concept of genus for plants.- Biography :...

. Although much disputed historically, the separation of Frangula from Rhamnus is now widely accepted, being supported by recent genetic data though a few authorities still retain the genus within Rhamnus (e.g. the Flora of China).

The genus name Frangula refers to the brittle wood. Both the English and scientific species names refer to its commonly growing together with alder

Alder

Alder is the common name of a genus of flowering plants belonging to the birch family . The genus comprises about 30 species of monoecious trees and shrubs, few reaching large size, distributed throughout the North Temperate Zone and in the Americas along the Andes southwards to...

s (Alnus) on damp sites. The name buckthorn

Buckthorn

The Buckthorns are a genus of about 100 species of shrubs or small trees from 1-10 m tall , in the buckthorn family Rhamnaceae...

 refers to its close relationship to the genus Rhamnus, though Alder Buckthorn does not have thorns. Other recorded names include glossy buckthorn and breaking buckthorn; historically, it was sometimes called "dogwood" through confusion of the leaves with those of Dogwood Cornus sanguinea.

Description

Alder Buckthorn is a deciduous shrub, growing to 3–6 m, occasionally to 7 m tall. It is usually multistemmed, but rarely forms a small tree with a trunk diameter of up to 20 cm. The bark

Bark

Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...

 is dark blackish-brown, with bright lemon-yellow inner bark exposed if cut. The shoots are dark brown, the winter buds without bud scales, protected only by the densely hairy outer leaves The leaves are ovate, 3–7 (–11) cm long by 2.5–4 (–6) cm wide, slightly downy on the veins, with an entire margin, 6–10 pairs of prominently grooved veins, and an 8–15 mm petiole; they are arranged alternately on the stems. The flower

Flower

A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...

s are small, 3–5 mm diameter, star-shaped with five greenish-white acute triangular petals, hermaphroditic

Plant sexuality

Plant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants....

, and insect pollinated, flowering in May to June in clusters of two to ten in the leaf axils. The fruit

Fruit

In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

 is a small black berry

Berry

The botanical definition of a berry is a fleshy fruit produced from a single ovary. Grapes are an example. The berry is the most common type of fleshy fruit in which the entire ovary wall ripens into an edible pericarp. They may have one or more carpels with a thin covering and fleshy interiors....

 6–10 mm diameter, ripening from green through red in late summer to dark purple or black in early autumn, containing two or three pale brown 5 mm seed

Seed

A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...

s. The seeds are primarily dispersed by frugivorous

Frugivore

A frugivore is a fruit eater. It can be any type of herbivore or omnivore where fruit is a preferred food type. Because approximately 20% of all mammalian herbivores also eat fruit, frugivory is considered to be common among mammals. Since frugivores eat a lot of fruit they are highly dependent...

 birds, which readily eat the fruit.

Ecology

Alder Buckthorn grows in wet soils in open woods, scrub, hedgerows and bogs, thriving well in sunlight and moderate shade, but less vigorously in dense shade; it prefers acidic soils though will also grow on neutral soils.

Frangula alnus is one of just two food plants (the other being Rhamnus cathartica) used by the Common Brimstone butterfly Gonepteryx rhamni. The flowers are valuable for bee

Bee

Bees are flying insects closely related to wasps and ants, and are known for their role in pollination and for producing honey and beeswax. Bees are a monophyletic lineage within the superfamily Apoidea, presently classified by the unranked taxon name Anthophila...

s, and the fruit an important food source for birds, particularly thrushes

Thrush (bird)

The thrushes, family Turdidae, are a group of passerine birds that occur worldwide.-Characteristics:Thrushes are plump, soft-plumaged, small to medium-sized birds, inhabiting wooded areas, and often feed on the ground or eat small fruit. The smallest thrush may be the Forest Rock-thrush, at and...

.

Cultivation and uses

Alder Buckthorn has limited decorative qualities without conspicuous flowers or bold foliage, and is mainly grown for its conservation value, particularly to attract Brimstone butterflies. A variegated

Variegation

Variegation is the appearance of differently coloured zones in the leaves, and sometimes the stems, of plants. This may be due to a number of causes...

 cultivar Frangula alnus 'Variegata' and a cultivar with very slender leaves 'Aslenifolia' are sometimes grown in gardens as ornamental shrubs. The cultivar 'Tallhedge' has been selected for hedging.

Invasive species

Frangula alnus was probably introduced to North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 about 200 years ago, and in Canada about 100 years ago. It was planted for hedgerows, forestry plantings, and wildlife habitat, but has become an invasive species

Invasive species

"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....

, invading forests in the northeastern United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and wetlands and moist forest in the Midwestern United States. It is predicted to continue to expand its North American range with time. Its invasiveness is assisted by its high adaptability and pollution tolerance.

It invades forests and grows in the understory in spots with a lot of light. These areas, usually where a tree has fallen, normally allow locally native tree seedlings to grow and eventually fill in the gap in the canopy. But when F. alnus invades and grows in these locations, its dense canopy prevents light from reaching the ground and therefore prevents other seedlings from growing. It tends to grow more densely and with larger individuals in lower topographical areas with moist, fertile soils, and is very problematic for land managers. Uplands forests are not invaded as easily as lower lying ones. Hemlock

Tsuga

Tsuga is a genus of conifers in the family Pinaceae. The common name hemlock is derived from a perceived similarity in the smell of its crushed foliage to that of the unrelated plant poison hemlock....

-oak

Oak

An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...

 stands, which tend to be older stands of trees, are much less suitable for F. alnus because the density of the tree canopy creates a more shady environment that is not as suitable for F. alnus. Eastern White Pine

Eastern White Pine

Pinus strobus, commonly known as the eastern white pine, is a large pine native to eastern North America, occurring from Newfoundland west to Minnesota and southeastern Manitoba, and south along the Appalachian Mountains to the northern edge of Georgia.It is occasionally known as simply white pine,...

 stands are easily invaded because they allow more light to reach the forest floor, and tree stands that are cut are very quickly invaded while undisturbed stands are rarely invaded.

Control

Small saplings can be hand-pulled, but control of larger examples is best achieved using herbicides. F. alnus and the related species Rhamnus cathartica

Rhamnus cathartica

Rhamnus cathartica , is a species in the family Rhamnaceae, native to Europe, northwest Africa, and western Asia, from the central British Isles south to Morocco, and east to Kyrgyzstan...

have been banned from sale, transport, or import to Minnesota

Minnesota

Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...

 and Illinois

Illinois

Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...

. It is considered invasive, but not banned, in Connecticut

Connecticut

Connecticut is a state in the New England region of the northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, and the state of New York to the west and the south .Connecticut is named for the Connecticut River, the major U.S. river that approximately...

.

Medicinal Purposes

Galen

Galen

Aelius Galenus or Claudius Galenus , better known as Galen of Pergamon , was a prominent Roman physician, surgeon and philosopher...

, a Greek physician of the 2nd century A.D., knew of Alder Buckthorn, although he did not distinguish clearly in his writings between it and other closely related species. All of these plants though, were credited with the power to protect against witchcraft, demons, poisons, and headaches.

The bark (and to a lesser extent the fruit) has been used as a laxative

Laxative

Laxatives are foods, compounds, or drugs taken to induce bowel movements or to loosen the stool, most often taken to treat constipation. Certain stimulant, lubricant, and saline laxatives are used to evacuate the colon for rectal and/or bowel examinations, and may be supplemented by enemas under...

, due to its 3 - 7% anthraquinone content. Bark for medicinal use is dried and stored for a year before use, as fresh bark is violently purgative; even dried bark can be dangerous if taken in excess.

Other uses

Alder Buckthorn charcoal is prized in the manufacture of gunpowder

Gunpowder

Gunpowder, also known since in the late 19th century as black powder, was the first chemical explosive and the only one known until the mid 1800s. It is a mixture of sulfur, charcoal, and potassium nitrate - with the sulfur and charcoal acting as fuels, while the saltpeter works as an oxidizer...

, being regarded as the best wood for the purpose. It is particularly highly valued for time fuses because of its very even burn rate. The wood was formerly used for shoe lasts, nails, and veneer. The bark yields a yellow dye, and the unripe berries furnish a green dye.