Rowan or Mountain Ash (Sorbus aucuparia)
The rowans are plants of the Family Rosaceae, in the Genus Sorbus, Subgenus Sorbus. They are native throughout the cool temperate regions of the northern hemisphere, with the highest species diversity in the mountains of western China and the Himalaya, where numerous apomictic microspecies occur. It has also become widely naturalised in northern North America. Based on their leaves Rowan are divided into the Aucuparia group with pinnate leaves and the Aria group with entire leaves.
Kingdom Plantae
Phylum Tracheophyta
Class Magnoliopsida
Order Rosales
Family Rosaceae
Genus Sorbus
The name "rowan" is derived from the Old Norse name for the tree, raun or rogn. Linguists believe that the Norse name is ultimately derived from a proto-Germanic word *raudnian meaning "getting red" and which referred to the red foliage and red berries in the autumn. Rowan is one of the most familiar wild trees in the British Isles, and has acquired numerous English folk names. The following are recorded folk names for the rowan: Delight of the eye (Luisliu), Mountain ash, Quickbane, Quickbeam, Quicken (tree), Quickenbeam, Ran tree, Roan tree, Roden-quicken, Roden-quicken-royan, Round wood, Royne tree, Rune tree, Sorb apple, Thor's helper, Whispering tree, Whitty, Wicken-tree, Wiggin, Wiggy, Wiky, Witch wood, Witchbane, Witchen, Witchen tree. Many of these can be easily linked to the mythology and folklore surrounding the tree. In Gaelic, it is Caorunn or Rudha-an (red one, pronounced quite similarly to English "rowan"), Welsh Cerddin, Irish Caorthann.
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One somewhat confusing name for the rowan, used in both the UK and North America, is "mountain ash", which implies that it is a species of ash (Fraxinus). The name arises from the superficial similarity in leaf shape of the two trees; in fact, the rowan does not belong to the ash family, but is closely related to the apples and hawthorns in the rose family. Rowan is in fact a member of the rose family (Rosaceae), and this misleading name has arisen only due to a superficial similarity in leaf shape of the two trees and an overlapping range.
This hardy tree inhabits cool to cold climates. Together with downy birch (Betula pubescens) and some willows (Salix spp.), it grows at the most northerly limit of trees in Europe, at latitude 70° north, in Finnmark in Norway, and is recorded at elevations of up to 2,000m in France. Five subspecies of rowan are recognised by scientists, and three of these have restricted distributions - one is limited to Bulgaria, another to northeastern Russia and a third to southern Italy, Sicily and Corsica. The other two subspecies are more widely distributed throughout the tree's range in Europe. Rowan grows in most parts of Britain, but is more common in the north and west, and is found throughout Scotland. It grows at a higher altitude than any other tree in the country and occurs at elevations of almost 1,000 metres in parts of the Highlands. In Scotland today, rowans are often found growing in inaccessible locations, such as cliffs, steep stream-sides and on top of large boulders. However, these are not the preferred locations for the species, but rather are the only places where it has been able to grow out of reach of herbivores such as red deer (Cervus elaphus) and sheep. Rowan prefers well-drained, peaty soils but is adaptable.
Classified as Least Concern (LC) in the British Red Data Book, indicating that rowan is widespread and abundant. A small to medium deciduous tree up to 4-12m tall but often smaller especially in exposed locations. It is slender in form, although mature trees can be quite substantial - an old rowan at Carnach Mor on the West Affric Estate has a trunk which is over 40 cm. in diameter. Its life span is estimated at 100 years or more. It coppices well and multi-stemmed forms are quite common, as a result of browsing by mammals and the subsequent production of basal shoots. The crown is initially elliptical but becoming wider with age. This tree has a deep tap root system which enables the plant to withstand high winds. It is a tree of western areas enjoying thin acid soils and is rarely, if ever, found on limestone or soft clays. Light and peaty soils not water logged up to 1000m. Pioneer species not tolerant of shading except in some Scots Pine woods. Commonest West and North of Britain but native throughout Britain and Ireland. Two species Sorbus aucuparia and S. aria are native in Ireland. Rowan trees can live up to an impressive 100 years or more.
The greyish-brown bark is smooth and shiny when wet, with dark raised dots or lenticels scattered with age, across it. The branches are typically upward-pointing and terminate in ovoid, purplish buds, which are often covered in grey hairs. The twigs are moderate to stout, pubescent early, becoming shiny gray-brown later in season, spur shoot present, leaf scars narrow, buds 3/8 to 1/2 inch long, reddish brown with long gray pubescences.
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It is unusual amongst Sorbus spp in having pinnately compound leavelets in 5 to 9 pairs, arranged alternately, 5 to 8 inches long, suggesting a source for the name Mountain ash since the leaves somewhat resemble the leaves of Fraxinus excelsior but unlike the true ash they have reddish-green midribs. The leaves are made up of matched pairs of leaflets on either side of a stem or rachis, with a terminal leaflet at the end. Individual leaflets are serrated, 1 to 1 1/2 inches long, dull dark green above paler below. Being a deciduous tree, rowan sprouts new leaves in April, which later turn a stunning bright orange-red colour in autumn before being shed.
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The small white flowers are produced in flat panicles in May and June after the leaves have appeared. The flowers are borne in dense corymbs 3 to 5 inches across, each containing up to 250 flowers; each flower is creamy white, and 5-10mm across with five petals and possess a distinctive strong, sweet scent. The strong, sweet scent attracts pollinating insects, including many species of flies, bees and beetles.
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Seed production begins when the tree is about 15 years old, and in mild climates, rowan will fruit each year. The fertilised flowers grow into berries which are 8 mm. in diameter and these ripen to a bright red colour in August or early September. However, in harsher environments such as Glen Affric, fruiting is irregular, and mast seed production, when all the trees produce a heavy crop, occurs every few years, with very little fruiting taking place in between.
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The berries are very attractive to fruit-eating birds, which is reflected in the old name "bird catcher". The fruit are soft and juicy, they are eaten primarily by birds, especially waxwings, mistle thrushes, chaffinches (Fringilla coelebs), siskins (Carduelis spinus), and blackbirds (Turdus merula), who disperse the seeds in their droppings. Rowan is used as a food plant by the larvae of some Lepidoptera species.
The berries are rich in ascorbic acid (vitamin C), and contain up to 8 small seeds, although 2 seeds per fruit is most common. The tough coat of the rowan seed requires cold weather to break down, and germination usually occurs in the first or second spring after the berries have been produced.
The berries can also be used to make jellies and to flavour apple-based preserves and are a traditional wild-collected food in Britain and Scandinavia.
Seedlings and saplings are shade-tolerant, and are often found under the branches of large Scots pines (Pinus sylvestris), where they have grown in the droppings of birds which perched on the branches above. For similar reasons, rowans also germinate
in the forks of the trunks of pines and other trees, but in most cases there is insufficient organic matter for these seedlings to grow to more than a metre or two in size. Exceptions to this do occur, and near Glac Daraich in Glen Affric there is a good example of a rowan which became established about two metres up an alder (Alnus glutinosa) and grew into a mature tree, partly embracing the alder, after its roots reached the soil below.
The wood is dense, hard, pale brown and used for carving and turning and for tool handles and walking sticks. Used to make bows in middle ages. Formerly used for tool handles, mallet heads, bowls and platters.
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Propagation and Growth:Grown from seed. Approx 200,000 seeds per kg.
Mythology & folklore
The European rowan (S. aucuparia) has a long tradition in European mythology and folklore. It was thought to be a magical tree and protection against malevolent beings.
The density of the rowan wood makes it very usable for walking sticks and magician's staves. This is why druid staffs, for example, have traditionally been made out of rowan wood, and its branches were often used in dowsing rods and magical wands. Rowan was carried on vessels to avoid storms, kept in houses to guard against lightning, and even planted on graves to keep the deceased from haunting. It was also used to protect one from witches. Often birds' droppings contain rowan seeds, and if such droppings land in a fork or hole where old leaves have accumulated on a larger tree, such as an oak or a maple, they may result in a rowan growing as an epiphyte on the larger tree. Such a rowan is called a "flying rowan" and was thought of as especially potent against witches and their magic, and as a counter-charm against sorcery. Rowan alleged protection against enchantment made it to be used in making rune staves, for metal divining, and to protect cattle from harm by attaching sprigs to their sheds. Leaves and berries were added to divination incense for better scrying.
In Finland and Sweden, the amount of berries on the trees was used as a predictor of the snow cover during winter. While this has been considered mere superstition, one hypothesis has been presented that genuine efficacy might stem from the causal connection of amount of berries and the amount of rainfall during summer. While in general no absolute connection between summer rainfall and snowfall in winter can be made, it is conceivable that in certain specific microclimates there might be some predictive value therein. This interpretation is supported by the fact that in some geographical areas, rowans replete with berries were thought to signify a thick snow cover, in others many berries meant very little snow.
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Fresh rowan berry juice is usable as a laxative, gargle for sore throats, inflamed tonsils, hoarseness, and as a source of vitamins A and C. Rowan berry jam will remedy diarrhea. An infusion of the berries will benefit hemorrhoids and strangury. The bark can also be used as an astringent for loose bowels and vaginal irritations. Rowan is also used for eye irritations, spasmic pains in the uterus, heart/bladder problems, neuralgia, gout and waist constrictions.
Rowan berries can be made into an excellent, slightly bitter, jelly which in Britain is traditionally eaten as an accompaniment to game, and into jams and other preserves, on their own, or with other fruits. The berries can also be a substitute for coffee beans, and have many uses in alcoholic beverages: to flavour liqueurs and cordials, to produce country wine, and to flavour ale.
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Rowan cultivars with superior fruit for human food use are available but not common; mostly the fruits are gathered from wild trees growing on public lands.
Rowan berries contain sorbic acid, an acid that takes its name from the Latin name of the genus Sorbus. Raw berries also contain parasorbic acid, which causes indigestion and can lead to kidney damage, but heat treatment (cooking, heat-drying etc.) and, to a lesser extent, freezing, neutralises it, by changing it to the benign sorbic acid. Luckily, they are also usually too astringent to be palatable when raw. Collecting them after first frost (or putting in the freezer) cuts down on the bitter taste as well.
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Ecological relationships of rowan
Rowan is an integral part of a conifer forest, where it grows in association with Scots pines, and it also occurs in oak (Quercus spp.) and birch (Betula spp.) woodlands. It rarely forms single-species stands of its own.
A variety of mycorrhizal fungi are associated with rowan, including an arbuscular mycorrhizal fungus (Glomus intradices) and an unusual ectomycorrhizal fungus (Cenoccum geophilum). In the symbiotic relationships formed by these fungi and the tree, both the partners benefit through an exchange of nutrients which each organism cannot access directly itself.
A rust fungus (Gymnosporangium cornutum) which infects juniper (Juniperus communis) spends its aecial or spore phase on rowan, where it produces galls which take the form of yellowish pustules on the upper surface of the leaves.
Rowan is a good host tree for lichens, and is the second best in the UK for Graphidion lichens (those which grow on smooth-barked trees) after hazel (Corylus avellana). Tree lungwort (Lobaria pulmonaria) is common on rowan trunks in areas with a wet climate or constant humidity, while a recently identified lichen (Arthothelium dictyosporum) which is endemic to Scotland occurs mainly on rowan.
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The foliage is palatable and highly attractive to browsing animals, and red deer will eat it in preference to most other tree species in the Caledonian Forest. Mountain hares (Lepus timidus) eat the leaves, and deer also feed on the bark and stems.
However, the larvae of several species of leaf-mining moths (Stigmella spp.) make mines in rowan leaves, and the caterpillars of the Welsh wave moth (Venusia cambrica) feed on the leaves. Larvae of the apple fruit moth (Argyresthia conjugella) are frequently found in the berries. A snail (Helix aspersa) has been shown to feed on the leaves, whilst a beetle (Byturus fumatus) feeds on the flowers, often completely eating the stamens.
The berries are eaten by a variety of birds in the forest, including chaffinches (Fringilla coelebs) and siskins (Carduelis spinus), while in towns and rural areas blackbirds (Turdus merula) are the main seed dispersers. Fieldfares (Turdus pilaris) and redwings (Turdus iliacus) time their migrations from Scandinavia to the UK to coincide with the availability of rowan berries, and in good fruit years, flocks of them will descend on the trees as they pass to the south. On their way, they will disperse the seeds, thereby enabling a new generation of young rowans to grow and take their place as a distinctive and beautiful feature of the Caledonian Forest.
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In contrast to many other broadleaved trees, the leaves are not palatable to phytophagous (ie plant-eating) insects, so comparatively few of them are associated with rowan.
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Feeding and other inter-species relationships Associated with Sorbus aucuparia
Food plant of
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is food plant of larva Anthonomus conspersus - a weevil (Coleoptera: Curculionidae) Bullock, J.A., 1992
Associate of
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is associate of imago Rhynchites cupreus - a leafroller weevil (Coleoptera: Attelabidae) Morris, M.G., 1990
Flower
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flower is visited by imago Hoplocampa alpina - a sawfly (Hymenoptera: Tenthredinidae) Benson, R.B., 1958
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Fruit
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developing fruit may contain larva Hoplocampa alpina - a sawfly (Hymenoptera: Tenthredinidae) Benson, R.B., 1958 [generally falls off when larva is mature]
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fruit may contain larva Rhynchites aequatus - Apple Fruit Rhynchites (Coleoptera: Attelabidae) Morris, M.G., 1990
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fruit may contain larva Rhynchites cupreus - a leafroller weevil (Coleoptera: Attelabidae) Morris, M.G., 1990, Bullock, J.A., 1992
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fruit may contain larva Anomoia purmunda - a gall fly (Diptera: Tephritidae) White, I.M., 1988
Leaf
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leaf (upperside) is grazed by flattened larva Dineura testaceipes - a sawfly (Hymenoptera: Tenthredinidae) Benson, R.B., 1958 [leaving lower cuticle intact]
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leaf is galled by Sappaphis sorbi (Homoptera: Aphididae) Stubbs, F.B. (Editor), 1986
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leaf is grazed by larva Trichiosoma sorbi - a clubhorned sawfly (Hymenoptera: Cimbicidae) Benson, R.B., 1951
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leaf is grazed by larva Priophorus brullei - a sawfly (Hymenoptera: Tenthredinidae) Benson, R.B., 1958
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leaf is grazed by colonial larva Pristiphora geniculata - a sawfly (Hymenoptera: Tenthredinidae) Benson, R.B., 1958
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leaf is grazed by nocturnal larva Tenthredo fagi - a sawfly (Hymenoptera: Tenthredinidae) Benson, R.B., 1952
Ovary
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ovary may house ovum Hoplocampa alpina - a sawfly (Hymenoptera: Tenthredinidae) Benson, R.B., 1958
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