This species grows as a shrub along the west coast of North America from Alaska to New Mexico. Further inland it is very much a species of the Rocky Mountains, though its range also extends to the eastern valleys of the Cascades. It particularly favours the lower forested slopes of foothills.
The Swedish whitebeam is a sturdy mid-sized tree reaching about 10m, with a broad round crown. It grows naturally along the coasts of the Baltic Sea, and sparsely in the south-west archipelago. The leaves are the main difference from the hybrid whitebeam (S. hybrida); the Swedish whitebeam’s leaf is shiny dark green above, sometimes even olive green, with shallow-lobed edges; on non-flowering shoots the leaves may have a single pair of leaflets near the base. The leaf undersides are grey or yellowish-felted.
We meet this friend almost everywhere in Finland, from rocky islets to stony ridges and right up into the Lapland Fells. The rowan or mountain ash grows further north than any other naturally growing member of the Sorbus genus. Finns have always valued it; it was regarded as sacred by their forefathers, and felling such a tree was believed to bring misfortune to the house. In a survey in the 1980s it was discovered that the species grows in every fourth garden in Finland.
At first sight, with the undersides of its white-felted leaves flickering in the wind, the common whitebeam doesn’t much resemble the typical mountain ash. Nevertheless it is a member of the large Eurasian genus of mountain ash (Sorbus), though there are many dendrologists who would like to see the whitebeams separated completely as their own genus of Aria. Typical of all 27 whitebeams species is that the leaves are (more or less) entire.
This hybrid mountain ash was first discovered in Finland, so can be regarded as a native. However, in addition to south-west Finland, it also grows naturally on Swedish islands and in Norway. Pietari Kalm called the tree S. fennica but nowadays it is called S. hybrida, the name given to it earlier by Linné, which acknowledged its hybrid status. Linné believed its parents to have been the rowan (S.aucuparia) and the Swedish whitebeam (S.
This mountain ash is one of the smallest and most attractive of the white berry rowans. The seeds develop without pollination and the seedlings are identical clones of the mother. It seems to grow to a maximum of 2 metres in about twenty years.
This species has stiff branches and an airy crown, its large flower corymbs and leaves giving it an almost tropical look. It bursts into growth early in spring – when other trees are still dormant this mountain ash’s sticky buds open; the emerald pencil-thick twigs and large leaves are soon on full summer display, despite late spring frosts.
Northern mountain ash, like American mountain ash, is native to north-eastern North America, where it typically grows along rocky river banks and lake shores. Compared with the native European mountain ash (S. aucuparia), this species is sturdier, with thicker branches and larger leaves. The large corymbs of flowers and bunches of fruit are showy, though the berries themselves are quite small. Together with the large attractive leaves and excellent hardiness, Northern mountain ash has deservedly become widely used in landscaping in Finland.
Chinese scarlet rowan grows over a wide range in eastern Asia, particularly in Japan and generally in mountainous areas. This very variable species was described for science by the Swedish rowan expert Theodor Hedlund. The first specimens were planted in Finland in the late 1950s but it has been commercially available only since the 1990s and is still rare, despite being both attractive and hardy.
American mountain ash is found throughout north-eastern North America, where it grows on moist slopes, at the edge of mires and among rocks. It closely resembles the European mountain ash (S. aucuparia), though often small and shrubby rather than tree-like. Another difference is in the terminal bud, which in this American species is somewhat sticky; in the European it is dry.