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Fraxinus

Fraxinus mandshurica var. mandshurica

The Manchurian ash resembles the native Finnish species, the European ash (F. excelsior), but its leaves are considerably larger and the shoots thicker; as if painted with a broader brush. The previous year’s shoots are bluntly angular. The wind-pollinated flowers appear before leaf flush and are polygamous, i.e. each tree can have flowers with male and female organs, or flowers which are only male or female, or any combination of any or all of these.

The large leaves are very similar to those of the North American black ash (F. nigra) and some botanists consider these two to be related subspecies. In the wild Manchurian ash grows in sparse mountain slope forests and open river valley groves in East Asia. It is naturally adapted to a continental climate, which makes it frost-hardier than Finland’s native ash, but at the same time much more susceptible to late spring frosts. This means that in Finland it is best suited to sheltered sites in eastern parts of the country.

 

Fraxinus rhynchophylla

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This ash grows in moist rich soils on hillsides and in river valleys over a wide range which extends from western China to Korea and the Russian Far East. The provenances grown in Finland are from the north-east parts of this range and there are two distinct forms: var. rhynchophylla has leaflets which are oval and come to a point, like most ashes; and var. densata, whose leaflets are large and broad, almost round, with a sandpapery rough surface.

In the wild the species can reach heights of 20 metres under good conditions but usually remains smaller. To reach full stature it needs sunshine and deep rich soil that retains some moisture.

Fraxinus rhynchophylla is one of the last of the ashes to break leaf in spring, usually avoiding the late frost damage that affects so many other ash species. Autumn colour comes early, which is a further indication of its suitability to the Finnish climate and brief growing season. Autumn colour varies between provenances and individuals from a dull orange-brown to a brilliant wine-red.

 

Fraxinus pennsylvanica - red ash

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The dioecious (i.e. individual trees are either male or female) red ash is native to North America, where it has the greatest range of any of the ash species. It has also been long grown in Finland, having proved hardier and less demanding than the native common ash (F. excelsior). The red ash has an attractive habit and is widely used in streets and parks.

The leaves of the red ash are slightly smaller than those of the common ash and have fewer leaflets. In winter the two trees can also be distinguished by bud colour, those of the local species being black, those of the red ash are brown. However, the smaller American tree with its multitude of branches can not match the majestic stature of the common ash.

The red ash can be seen at Mustila as a small stand west of Tammimetsä (Oak Forest). It prefers full sun, is untroubled by severe winds and is quite happy in dry or moist soil. It takes on bright yellow colour early in autumn, glowing against the blue of the sky.

 

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