The Swedish whitebeam (Sorbus intermedia)

The Swedish whitebeam (Sorbus intermedia), with its grey green leaves, creamy white flowers and red berries, is widespread in the British Isles though not a native tree. It is frequent in parks and gardens, and is a tough and popular street tree, though in the latter case often confused with the similar Sorbus mougeotii, the Vosges or Mougeot’s whitebeam. It also resembles the English whitebeam (Sorbus anglica). The Swedish whitebeam is also naturalised quite widely into urban and countryside habitats in Britain and mainland Europe outside its native range usually, no doubt, being bird sown.

Sorbus intermedia occurs as a native in southern Sweden (where it is known as the oxel) and various other countries mainly around the Baltic sea. It is a triploid apomictic species which breeds true from seed that have not been pollinated and is thought to have a parentage derived from the mountain ash (Sorbus aucuparia), the wild service (S. torminalis) and a member of the whitebeam aggregate (S. aria agg.). S. aucuparia and S. torminalis occur on the Danish island of Bornholm in the Baltic as does Sorbus rupicola, a member of the aria group, and S. intermedia itself, though I think this only shows that conditions may occur in the wild where all the species thought to be involved in the genome of S. intermedia can be present together.

It has also been suggested that S. intermedia possibly arose as a cross between the Finnish whitebeam (Sorbus hybrida) and S. aucuparia.

In the north of England, particularly in North Yorkshire, Durham, Northumberland and southern Scotland, the Swedish Whitebeam is commonly called ‘the service tree’ and this has led to a number of incorrect records of the wild service (S. torminalis), both from the area concerned and from other places which people who come from the north have visited or moved to (Roper, 1993). While it is not regarded as a native in Britain, this may indicate an early introduction of the Swedish whitebeam into northern England and southern Scotland through links between the north east coast and Scandinavia.

In his Flora Oeconomica Linnaeus wrote that bears were very fond of Swedish whitebeam berries and that bread could be made from the fruit after drying, a spirit distilled and a drink brewed from them (Anderberg & Anderberg, 2010) . This is a set of attributes often ascribed to other Sorbus species. The use in brewing would appear to be equivalent to the diod griafol fermented drink made from rowan berries in Wales. The fruit of the Swedish whitebeam appears to be little used today, but the wood in stabilised form is available for small turnery items, knife handles and similar.

There are many pictures of the Swedish whitebeam and its relatives on-line and a particularly telling sequence of photographs is that of an old, free-standing tree near Välsta in southern Sweden by Stefan Jansson: http://www.flickr.com/photos/steffe/sets/1794272/comments/

It is a large, wide-spreading example similar in shape to old, open-grown wild services and, somehow, it looks like a native plant compared with those in the British Isles.

REFERENCES

Anderberg, A. & Anderberg, A-L. (2010) Den virtuella floren. Naturhistoriska riksmuseet, Stockholm.

Roper, P. (1993) The distribution of the Wild Service Tree, Sorbus torminalis (L.) Crantz, in the British Isles. Watsonia 19:209-229.

Sell, P. D. (1989) The Sorbus latifolia (Lam.) Pers. aggregate in the British Isles. Watsonia 17: 385-399