The Useful Betulaceae!

Showing the very recognizable stems of our native Silver Birch.
The very recognizable stems of the Silver Birch at Cannock Chase

After all the short flowering plants, this time a blog on the woody trees called Betulaceae, which includes the main genus, Betula or Birch but also our native Alder, Hornbeam and Hazel belong in this family.

The Betulaceae or Birch Family is number 55 in Stace and has 3 straight native species of Birch as well as several hybrids, subspecies and introduced, ornamental varieties.

The birch is a typical pioneer, which means it can colonize new land very rapidly in the right conditions and can therefore be seen as a weed by some who wouldn’t like them to do this!

But most of us can agree that the Birch tree is very beautiful and hoping for you to learn in the following text that it is also a very useful tree as are its cousins, Alder, Hornbeam and Hazel about which I will tell you more in the second part!

The three species we know here in Britain are:

Betula pendula or Silver Birch with its typical white bark. This can form woods on light, mostly acid soils, especially heathland, and usually it grows in drier places than the second species:

B. pubescens or Downy Birch, which is the other native tree, growing in similar places but favouring wetter and more peaty soils, especially in upland. The bark can be brown, grey or white but rarely white with strongly contrasting black fissures below and twigs in mature trees usually not pendent.

B. nana or Dwarf Birch is a shrub to 1 meter, with procumbent to ascending stems; twigs stiff and hairy. This is a much less common native of upland moors and bogs on peat.

The ecology of Silver Birch is an interesting read at Wikipedia, attracting many life forms:

The silver birch has an open canopy which allows plenty of light to reach the ground. This allows a variety of mosses, grasses, and flowering plants to grow beneath, which in turn attract insects. Flowering plants often found in birch woods include primrose (Primula vulgaris), violet  (Viola riviniana), bluebell (Hyacinthoides non-scripta), wood anemone (Anemone nemorosa), and wood sorrel  (Oxalis acetosella). Small shrubs that grow on the forest floor include blaeberry (Vaccinium myrtillus) and cowberry  (Vaccinium vitis-idaea) Birds found in birch woodland include the chaffinchtree pipitwillow warblernightingalerobinwoodcockredpoll, and green woodpecker

The branches of the silver birch often have tangled masses of twigs known as witch’s brooms growing among them, caused by the fungus Taphrina betulina. Old trees are often killed by the decay fungus Piptoporus betulinus and fallen branches rot rapidly on the forest floor. This tree commonly grows with the mycorrhizal fungnseus Amanita muscaria in a mutualistic relationship. This applies particularly to acidic or nutrient-poor soils. Other mycorrhizal associates include Leccinum scabrum and Cantharellus cibarius. In addition to mycorrhiza, the presence of microfauna in the soil assists the growth of the tree, as it enhances the mobilization of nutrients.

Birch sawfly (Craesus septentrionalis) larvae feeding on silver birch, West Wales, July 2014

The larvae of a large number of species of butterflies, moths, and other insects feed on the leaves and other parts of the silver birch. In Germany, almost 500 species of insects have been found on silver and downy birch including 106 beetles and 105 lepidopterans, with 133 insect species feeding almost exclusively on birch. Birch dieback disease can affect planted trees, while naturally regenerated trees seem less susceptible. This disease also affects B. pubescens and in 2000 was reported at many of the sites planted with birch in Scotland during the 1990s. In the United States, the wood is attacked by the bronze birch borer (Agrilus anxius), an insect pest to which it has no natural resistance.

It is an attractive ornamental tree, especially during the winter months, the silver birch is often planted therefore in parks and gardens, grown for its white bark, open airy habit and gracefully drooping shoots. The young foliage is light green in early spring and a butter yellow in autumn.

Many other uses can be found in Wikipedia:

In Scandinavia and other regions of northern Europe, it is grown for

  • forest products such as lumber and pulp, as well as for aesthetic purposes and ecosystem services.
  • It is sometimes used as a pioneer and nurse tree elsewhere.

Silver birch wood is pale in colour with no distinct heartwood and is used in making

  • furniture, plywood, veneers, parquet blocks, skis, and kitchen utensils, and in turnery.
  • It makes a good firewood that produces a good heat when burnt, but is quickly consumed by the flames.
  • Slabs of bark are used for making roof shingles and
  • strips are used for handicrafts such as wooden footwear and small containers.
  •  Historically, the bark was used for tanning.
  • Bark can be heated and the resin collected; the resin is an excellent waterproof glue and useful for starting fires.
  •  The thin sheets of bark that peel off young wood contain a waxy resin and are easy to ignite even when wet.
  •  The dead twigs are also useful as kindling for outdoor fires.
  • Birch brushwood is used for racecourse jumps and besom brooms.
  • In the spring, large quantities of sap rise up the trunk and this can be tapped. It contains around 1% sugars and can be used in a similar way to maple syrup, being drunk fresh, concentrated by evaporation, or fermented into a “wine”.
  • In Sweden, the bark of birch trees was ground up and used to make bark bread, a form of famine food. The removal of bark was at one time so widespread that Carl Linnaeus expressed his concern for the survival of the woodlands.
A pair of Finnish traditional shoes woven from strips of birch bark (Wikipedia)

The silver birch is Finland’s national tree. Leafy, fragrant boughs of silver birch (called vihta or vasta) are used to gently beat oneself in the Finnish sauna culture.

The strong and water-resistant cardboard-like bark can be easily cut, bent, and sewn, which has made it a valuable building, crafting, and writing material, since pre-historic times.

Even today, birch bark remains a popular type of wood for various handicrafts and arts.

Birch bark also contains substances of medicinal and chemical interest. Some of those products (such as betulin) also have fungicidal properties that help preserve bark artifacts, as well as food preserved in bark containers.                                                                                                      

From the Medicinal Flora:

It is a tree of Magic for the Nordic peoples, which is not surprising considering its versatility. Birch oil has other applications as well as the medicinal and is a constituent of Russian Ointment, which is applied to stiff muscles and joints. Not only is the oil used in medicinal steam baths but also the twigs are bound into a bundle as a flagellant for use in saunas. As an internal remedy it is hardly used in Britain and, just in this sense, we should bring back the Birch.

Parts used: The leaves, harvested in March to July; the buds, bark and sap are harvested in the spring. Various parts of the wood are used in birch tar preparations.

Action: Diuretic, diaphoretic, anti inflammatory, anti-micrbal, astringent, analgesic (not potent but useful in combination). Said to improve renal uric acid excretion.

Uses: Kidney and urinary tract infections. Albuminaria, oligaria. Oedema associated with poor renal function and low cardiac output. Gout, renal colic (claims for Litholytic effects poorly substantiated). Rheumatic pain (both internally & externally). Aids in the healing of wounds, sores and ulcers.

Downy birch extends farther north into the Arctic than any other broadleaf tree. This variety is notable as being one of very few trees native to Iceland and Greenland, and is the only tree to form woodland in Iceland. At one time the island is thought to have been covered in downy birch woodland, but that cover is reduced to about one percent of the land surface today.

Its ecology is again fascinating:

The larva of the autumnal moth (Epirrita autumnata) feeds on the foliage of Betula pubescens and other tree species. In outbreak years, large areas of birch forest can be defoliated by this insect. Damage to the leaf tissue stimulates the tree to produce chemicals that reduce foliage quality, retarding the growth of the larvae and reducing their pupal weights.

In Greenland, about seventy species of fungi have been found growing in association with  B. pubescens, as parasites or saprobes on living or dead wood. Some of the most common fungi include Ceriporia reticulataChondrostereum purpureum, Exidia repanda, Hyphoderma spp,  Inonotus obliquusInonotus radiatusMycena galericulataMycena rubromarginataPanellus ringensPeniophora incarnataPhellinus lundelliiRadulomyces confluensStereum rugosumTrechispora spp., Tubulicrinis spp. and Tyromyces chioneus.

Birch dieback disease, associated with the fungal pathogens Marssonina  betulae and Anisogramma virgultorum, can affect planted trees, while naturally regenerated trees seem less susceptible. This disease also affects Betula pendula and in 2000 was reported at many of the sites planted with birch in Scotland during the 1990s.

Main Uses:

  • The outer layer of bark can be stripped off the tree without killing it and can be used to make canoe skins, drinking vessels and roofing tiles.
  • The inner bark can be used for the production of rope and for making a form of oiled paper.
  • This bark is also rich in tannin and has been used as a brown dye and as a preservative.
  • The bark can also be turned into a high quality charcoal favoured by artists.
  • The twigs and young branches are very flexible and make good whisks and brooms.
  •  The timber is pale in colour with a fine, uniform texture and is used in the manufacture of plywood, furniture, shelves, coffins, matches and toys, and in turnery.
  • Both B. pubescens and B. pendula can be tapped in spring to obtain a sugary fluid. This can be consumed fresh, concentrated into a syrup similar to the better-known maple syrup, or can be fermented into an ale or wine.

The Sami people of Scandinavia used the bark of both B. pubescens and B. pendula as an ingredient in bread-making; the reddish phloem, just below the outer bark, was dried, ground up and blended with wheat flour to make a traditional loaf.

In Finlandmämmi, a traditional Easter food, was packed and baked in boxes of birch bark. Nowadays, cardboard boxes are used, but imprinted with the typical bark pattern.Birch bark was used as an emergency food in times of famine; in Novgorod in 1127–28, desperate people ate it along with such things as the leaves of lime trees, wood pulp, straw, husks and moss.In Iceland, trimmings of birch trees are used with birch sap in the making of a sweet birch liqueur. The leaves can be infused with boiling water to make a tea, and extracts of the plant have been used as herbal remedies.

Medicinal Uses of the Downy Birch (B. pubescens):

It is less commonly employed but in the same manner as the preceeding species. The leaves of both species can be used to make a ‘dry bat’ for rheumatic pain.

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