Frangula alnus | |
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Foliage with mature and immature fruit | |
Scientific classification ![]() | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Rosales |
Family: | Rhamnaceae |
Genus: | Frangula |
Species: | F. alnus |
Binomial name | |
Frangula alnus | |
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Distribution map | |
Synonyms [2] [3] | |
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Frangula alnus, commonly known as alder buckthorn, glossy buckthorn, or breaking buckthorn, is a tall deciduous shrub in the family Rhamnaceae. Unlike other "buckthorns", alder buckthorn does not have thorns. It is native to Europe, northernmost Africa, and western Asia, from Ireland and Great Britain north to the 68th parallel in Scandinavia, east to central Siberia and Xinjiang in western China, and south to northern Morocco, Turkey, and the Alborz in Iran and the Caucasus Mountains; in the northwest of its range (Ireland, Scotland), it is rare and scattered. It is also introduced and naturalised in eastern North America. [4] [5] [6] [7]
Alder buckthorn is a non-spiny deciduous shrub, growing to 3–6 m (10–20 ft), occasionally to 7 m (23 ft) tall. It is usually multistemmed but rarely forms a small tree with a trunk diameter of up to 20 cm (8 in). The bark 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 arranged alternately on 8–15-millimetre (5⁄16–19⁄32-inch) petioles. They are ovate, 3–7 cm (1+1⁄4–2+3⁄4 in) long by 2.5–4 cm (1–1+5⁄8 in) wide (rarely to 11 cm or 4+1⁄4 in by 6 cm or 2+1⁄4 in). They have 6–10 pairs of prominently grooved and slightly downy veins and an entire margin.
The flowers are small, 3–5 mm (1⁄8–3⁄16 inch) in diameter, star-shaped with five greenish-white acute triangular petals, hermaphroditic, and insect-pollinated, flowering in May to June in clusters of two to ten in the leaf axils.
The fruit is a small black berry 6–10 mm (1⁄4–13⁄32 inch) in diameter, ripening from green through red in late summer to dark purple or black in early autumn, containing two or three pale brown 5-millimetre (3⁄16-inch) seeds. The seeds are primarily dispersed by frugivorous birds, which readily eat the fruit. [4] [6] [7] [8] [9]
Alder buckthorn was first formally described by Carl Linnaeus in 1753 as Rhamnus frangula. It was subsequently separated by Philip Miller in 1768 into the genus Frangula on the basis of its hermaphrodite flowers with a five-parted corolla (in Rhamnus the flowers are dioecious and four-parted); this restored the treatment of pre-Linnaean authors, notably Tournefort. [10] Although much disputed historically, the separation of Frangula from Rhamnus is now widely accepted, being supported by recent genetic data [11] though a few authorities still retain the genus within Rhamnus (e.g., the Flora of China [7] ).
The genus name Frangula, from Latin frango "to break", refers to the brittle wood. Both the common name alder buckthorn and specific epithet alnus refer to its association with alders (Alnus) on damp sites. Unlike other "buckthorns", alder buckthorn does not have thorns. [12] [8] 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. [12]
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. [6] [12] [9]
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 bees, and the fruit an important food source for birds, particularly thrushes. [8]
Frangula alnus was probably introduced to North America 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, invading forests in the northeastern United States and wetlands and moist forest in the Midwestern United States. [13] [14] [15] It is predicted to continue to expand its North American range with time. [13] Its invasiveness is assisted by its high adaptability and pollution tolerance. [16] It is one of three species of buckthorn that occurs without cultivation in eastern Canada. [17]
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 Frangula alnus invades and grows in these locations, its dense canopy prevents light from reaching the ground and therefore prevents other seedlings from growing. [16] 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-oak stands, which tend to be older stands of trees, are much less suitable for Frangula alnus because the density of the tree canopy creates a more shady environment that is not as suitable for Frangula alnus. Eastern 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. [18]
Although considered an invasive species in North America, In other places, such as Northern Ireland, Frangula alnus has suffered greatly from habitat loss. [19] This is due to the decline in its preferred habitats, which are boglands. [19] [20] It is currently only found on the southern side of Lough Neagh, but it the past, it was also found on the northern side of the lake. [21] Compared to other populations of Frangula alnus, the population in Ireland also has lower genetic diversity. [19] [22]
Small saplings can be hand-pulled, but control of larger examples is best achieved using herbicides. [23] Frangula alnus and the related species Rhamnus cathartica have been banned from sale, transport, or import to Minnesota [24] and Illinois. [25] It is considered invasive, but not banned, in Connecticut. [26]
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 cultivar Frangula alnus 'Variegata' and a cultivar with very slender leaves 'Asplenifolia' are sometimes grown in gardens as ornamental shrubs. The cultivar 'Tallhedge' has been selected for hedging. [27]
Galen, 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.[ citation needed ]
The bark (and to a lesser extent the fruit) has been used as a laxative, 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. [4] [27]
Alder buckthorn charcoal is prized in the manufacture of gunpowder, being regarded as the best wood for the purpose. It is particularly highly valued for time fuses because of its very even burn rate. [4] [12] 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. [27]
Alnus glutinosa, the common alder, black alder, European alder, European black alder, or just alder, is a species of tree in the family Betulaceae, native to most of Europe, southwest Asia and northern Africa. It thrives in wet locations where its association with the bacterium Frankia alni enables it to grow in poor quality soils. It is a medium-sized, short-lived tree growing to a height of up to 30 metres (98 feet). It has short-stalked rounded leaves and separate male and female flowers in the form of catkins. The small, rounded fruits are cone-like and the seeds are dispersed by wind and water.
Rhamnus is a genus of about 140 accepted species of shrubs or small trees, commonly known as buckthorns, in the family Rhamnaceae. Its species range from 1 to 10 m tall and are native mainly in east Asia and North America, but found throughout the temperate and subtropical Northern Hemisphere, and also more locally in the subtropical Southern Hemisphere in parts of Africa and South America. One species, the common buckthorn, is able to flourish as an invasive plant in parts of Canada and the United States, where it has become naturalized.
Alnus incana, the grey alder, tag alder or speckled alder, is a species of multi-stemmed, shrubby tree in the birch family, with a wide range across the cooler parts of the Northern Hemisphere. Tolerant of wetter soils, it can slowly spread with runners and is a common sight in swamps and wetlands.
Alnus cordata, the Italian alder, is a tree or shrub species belonging to the family Betulaceae, and native to the southern Apennine Mountains and the north-eastern mountains of Corsica. It has been introduced in Sicily, Sardinia, and more recently in Central-Northern Italy, other European countries and extra-European countries, where it has become naturalised.
Frangula is a genus of about 35 species of flowering shrubs or small trees, commonly known as alder buckthorn in the buckthorn family Rhamnaceae. The common name buckthorn is also used to describe species of the genus Rhamnus in the same family and also sea-buckthorn, Hippophae rhamnoides in the Elaeagnaceae.
Frangula californica is a species of flowering plant in the buckthorn family native to western North America. It produces edible fruits and seeds. It is commonly known as California coffeeberry and California buckthorn.
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Rhamnus cathartica, the European buckthorn, common buckthorn, purging buckthorn, or just buckthorn, is a species of small tree in the flowering plant family Rhamnaceae. It is native to Europe, northwest Africa and western Asia, from the central British Isles south to Morocco, and east to Kyrgyzstan. It was introduced to North America as an ornamental shrub in the early 19th century or perhaps before, and is now naturalized in the northern half of the continent, and is classified as an invasive plant in several US states and in Ontario, Canada.
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Bucculatrix frangutella is a moth of the family Bucculatricidae. It was described by Johann August Ephraim Goeze in 1783. It is found in Europe.
Rhamnus alnifolia is a species of flowering plant in the buckthorn family known by the common names alderleaf buckthorn, or alder buckthorn. Unlike other "buckthorns", this alder buckthorn does not have thorns. It is native to North America, and can be found in forested habitat.
Frangula rubra is a species of flowering plant in the buckthorn family known by the common names red buckthorn and Sierra coffeeberry.
Frangula betulifolia, the birchleaf buckthorn, is a shrub or small tree in the buckthorn family, Rhamnaceae. It is native in northern Mexico in the Sierra Madre Occidental cordillera, and mountainous, desert regions of the Southwestern United States of Arizona, Utah, New Mexico, and far west Texas; besides being found in Sonora, Chihuahua and Durango of the Occidental cordillera, a large species locale occurs to the east in Nuevo León.
Rhamnus alaternus is a species of flowering plant in the buckthorn family Rhamnaceae, known by the common names Italian buckthorn or Mediterranean buckthorn. It is a hardy medium-sized evergreen shrub with fragrant flowers.
Alnus alnobetula is a common tree widespread across much of Europe, Asia, and North America. Many sources refer to it as Alnus viridis, the green alder, but botanically this is considered an illegitimate name synonymous with Alnus alnobetula subsp. fruticosa.
Ancylis obtusana, the small buckthorn roller, is a moth of the family Tortricidae.