Sorbus aucuparia, commonly called rowan (, also ) and mountain-ash, is a species of deciduous tree or shrub in the rose family.

The tree has a slender trunk with smooth bark, a loose and roundish crown, and its leaves are pinnate in pairs of leaflets on a central vein with a terminal leaflet. It blossoms from May to June in dense corymbs of small yellowish white flowers and develops small red pomes as fruit that ripen from August to October and are eaten by many bird species.

It is a highly variable species, and botanists have used different definitions of the species to include or exclude trees native to certain areas. A recent definition includes trees native to most of Europe and parts of Asia, as well as northern Africa. The range extends from Madeira, the British Isles and Iceland to Russia and northern China. Unlike many plants with similar distributions, it is not native to Japan. The crown is loose and roundish or irregularly shaped but wide and the plant often grows multiple trunks. A trunk is slender and cylindrical and reaches up to in diameter, and the branches stick out and are slanted upwards. The bark of a young plant is yellowish gray and gleaming and becomes gray-black with lengthwise cracks in advanced age; it descales in small flakes. The plant does not often grow older than 80 years and is one of the shortest-lived trees in temperate climate. The wood has a wide reddish white sapwood and a light brown to reddish brown heartwood. It is diffuse-porous, flexible, elastic, and tough, but not durable, with a density of in a dried state. and are arranged alternately along a branch, Leaflets are covered in gray-silvery hairs after sprouting but become mostly bare after they unfold. Their upper side is dark green and their underside is a grayish green and felted. Young leaflets smell like marzipan when brayed. The leaflets are asymmetrical at the bottom.

The buds are often longer than and have flossy to felted hairs. The corymbs are large, upright, and bulging. The flowers are between in diameter and have five small, yellowish green, and triangular sepals that are covered in hairs or bare. A corymb carries 80 to 100 pomes. A pome contains a star-shaped ovary with two to five locules each containing one or two flat, narrow, and pointed reddish seeds. Its fruit persists for an average of 100.6 days, and bears an average of 2.5 seeds per fruit. Fruits average 73.0% water, and their dry weight includes 8.9% carbohydrates and 3.1% lipids.

The species has a chromosome number of 2n=34.

Taxonomy

Fossil record

Fossils of Sorbus aucuparia have been described from the fossil flora of Kızılcahamam district in Turkey, which is of early Pliocene age.

Names

The binomial name Sorbus aucuparia is composed of the Latin words sorbus for service tree and aucuparia, which derives from the words avis for "bird" and capere for "catching" and describes the use of the fruit of S. aucuparia as bait for fowling. The names rowan and mountain ash may be applied to other species in Sorbus subgenus Sorbus, and mountain ash may be used for several other distantly related trees. The species is not closely related to either the true ash trees (genus Fraxinus), which also carry pinnate leaves, or the species Eucalyptus regnans, also called mountain ash, native to Tasmania and Victoria in southeastern Australia.

The common name mountain ash dates from the 16th century. It was first used by John Gerard in 1597, translating it directly from the then botanists' Latin Montana fraxinus

S. aucuparia was previously categorized as Pyrus aucuparia.

Distribution and habitat

thumb|upright=1.3|alt=photo|Growing with [[mountain pine in the Italian Alps]]

Sorbus aucuparia is found in five subspecies:

  • Sorbus aucuparia subsp. aucuparia: found in most of the species' range, less in the South
  • Sorbus aucuparia subsp. fenenkiana (Georgiev & Stoj.): has thin, sparsely hairy leaflets and depressed-globose fruit, restricted to Bulgaria
  • Sorbus aucuparia subsp. glabrata (Wimm. & Grab.): less hairy, found in Northern Europe and Central European mountains
  • Sorbus aucuparia subsp. praemorsa (Guss.): has hairy leaflets and ovoid fruit, found in Southern Italy, Sicily, and Corsica
  • Sorbus aucuparia subsp. sibirica (Hedl.): nearly hairless, found in North Eastern Russia

It can be found in almost all of Europe and the Caucasus up to Northern Russia and Siberia, but it is not native to Southern Spain, Southern Greece, Sardinia, the Balearic Islands, the Azores, and the Faroe Islands. The species was introduced as an ornamental species in North America. The plant is also resistant to air pollution, wind, and snow pressure. It mostly grows on soil that is moderately dry to moderately damp, acidic, low on nutrients, sandy, and loose. It often grows in stony soil or clay soil, but also sandy soil or wet peat. It can be found in light woodland of all kinds and as a pioneer species over fallen dead trees or in clearcuttings, and at the edge of forests or at the sides of roads. In Germany, an unusually large specimen is located near Wendisch Waren, a village in Mecklenburg-Vorpommern. This tree stands at more than tall, is around 100 years old, and has a diameter of . The tallest known specimen in Ireland is an tall specimen at Glenstal Abbey, County Limerick.

Ecology

thumb|alt=Trunk with exposed rectangular area of peeled wood through nearly half the trunk thickness, at perhaps breast height|Damage caused by game animal

The species is pollinated by bees and flies. The fruit are eaten by about 60 bird species and several mammals. They are liked particularly by thrushes and other songbirds, and are also eaten by cloven-hoofed game, red fox, European badger, dormouse, and squirrel. In Central Europe it often grows in association with red elderberry, goat willow, Eurasian aspen, and silver birch.

Other species of the genus Sorbus easily hybridize with S. aucuparia and hybrid speciation can result; hybrids include Sorbus × hybrida, a small tree with oval serrated leaves and two to three pairs of leaflets, which is a hybrid with Sorbus × intermedia, and S. thuringiaca, a medium-size tree with elongated leaves and one to three pairs of leaflets that are sometimes fused at the central vein, which is a hybrid with S. aria.

The main pests for S. aucuparia are the apple fruit moth Argyresthia conjugella and the mountain-ash sawfly Hoplocampa alpina. The rust fungus Gymnosporangium cornutum produces leaf galls. The leaves are not palatable to insects, but are used by insect larvae, including by the moth Venusia cambrica, the case-bearer moth Coleophora anatipennella, and leaf miners of the genus Stigmella. The snail Cornu aspersum feeds on the leaves.

Uses

Culinary

The fruit of S. aucuparia were used in the past to lure and catch birds. To humans, the fruit are bitter, astringent, laxative, diuretic and a cholagogue. They have vitamin C, so they prevent scurvy, but the parasorbic acid irritates the gastric mucosa. The fruit contain sorbitol, which can be used as a sugar substitute by diabetics, but its production is no longer relevant. Sorbus aucuparia fruits have been used in the traditional Austrian medicine internally (as tea, syrup, jelly or liqueur) for treatment of disorders of the respiratory tract, fever, infections, colds, flu, rheumatism and gout.

Due to their bitterness, raw rowan berries normally are not very palatable, but can be debittered and made into compote, jelly, jam, a tart syrup or chutney, pressed into juice. It is also used to make wine, liqueurs, teas, and flour. Fruit are served as a side dish to lamb or game. The robust qualities of S. aucuparia make it a source for fruit in harsh mountain climate and Maria Theresa, ruler of the Habsburg monarchy, recommended the planting of the species in 1779. Its leaves are larger and pointed, only the front part of the leaflets is serrated, and they have darker bark, larger buds and larger fruit. Similar non-bitter varieties found in Southern Russia were first introduced in Central Europe in 1900 as 'Rossica' and 'Rossica Major', which has large fruit up to in diameter.

Two widespread cultivars of the Moravian variety are 'Konzentra' and 'Rosina', which were selected beginning in 1946 by the Institut für Gartenbau Dresden-Pillnitz, an agricultural research institute in Saxony, from 75 specimens found mostly in the Ore Mountains, and made available in 1954. The two cultivars are self-pollinating, yield fruit early, and the sugar content increases while the acid content decreases as the fruit ripen. 'Beissneri' is a cultivar with reddish foliage and bark and serrated leaves.

Russian botanist Ivan Vladimirovich Michurin began in 1905 to crossbreed common S. aucuparia with other species to create fruit trees. His experiments resulted in the cultivars 'Burka', 'Likjornaja', 'Dessertnaja', 'Granatnaja', 'Rubinovaja', and 'Titan'.

The leaves were fermented with leaves of sweet gale and oak bark to create herb beer.

The species is planted in mountain ranges to fortify landslide and avalanche zones.

'Sheerwater Seedling', an upright and slender cultivar, and 'Wisley Gold' with yellow fruits, have received the Royal Horticultural Society's Award of Garden Merit.

Cultivars are vegetatively propagated via cuttings, grafting, or shield budding.

In English folklore, twigs of S. aucuparia were believed to ward off evil spirits The plant was called "the witch" in England and dowsing rods to find ores were made out of its wood. The wooden shafts of forks and other farm implements were constructed from the species to protect farm animals and production from witches' spells.

S. aucuparia is used in the coats of arms of the German municipalities Ebernhahn, Eschenrode, and Hermsdorf, and of the Vysočina Region of the Czech Republic. Rowan is part of the coat of arms of the Metropolitan Borough of Wigan and the logo of both Wigan Athletic and Wigan Warriors.

Footnotes

References

  • Sorbus aucuparia - information, genetic conservation units and related resources. European Forest Genetic Resources Programme (EUFORGEN)