Skip to main content

Sorbus

Sorbus frutescens - helmipihlaja

sorbus_koehneana_marjaoksat_kumpula_jreinikainen.jpg

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.

The twigs are chocolate brown and the egg-shaped buds almost black. The compound leaves have on average 9-13 pairs of leaflets. The inflorescence is a loose white corymb. The white berries are quite large, about the same size as the mountain ash Sorbus aucuparia, with a touch of pink where the calyxes were.

Joseph Rock was an Austrian emigrant to the United States and a versatile naturalist; he collected this species in the Gansun province of China. It has been grown in continental Europe and Scandinavia since 1924, and is still usually called – mistakenly – S. koehneana; the true S. koehneana grows to five metres but is not grown in Europe at all, practically speaking.

 

Sorbus ulleungensis 'Dodong'

Sorbus 'Dodong' ©Susanna

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.

‘Dodong’ flowers in June, somewhat later than the European species S. aucuparia. The white flower corymbs are especially large. The resulting big berries are slightly drop-shaped, orange-red, and in large bunches. On sunny sites, the large leaves take on brilliant orange-red autumn coloration.

The species originates from Ullung Island in the Sea of Japan, about 120 kms from the Korean coast, where there are dozens of unique plants as a result of its isolated position and its freedom from glaciation during the last ice age.

’Dodong’ seed was collected by the Swedish botanist Tor Nitzelius in 1976. One of the seedlings from this collection was selected and has been vegetatively propagated, quickly becoming an established garden favourite.

’Dodong’ came to Mustila in 1992 as a 90th anniversary gift from Sweden, probably the first of its kind in Finland. It is growing on Etelärinne, or Southern slope. It was attacked by hares immediately after planting, but saved by Axel Tigerstedt’s prompt treatment of the damaged bark with wax. Shaded by other trees, it has not achieved its full glory. In addition to this single specimen, Mustila also has young plants growing from seed collected from a stand growing in Gothenburg.

 

Sorbus decora - Northern mountain ash

sorbus_decora_kukinto_kumpula_jreinikainen.jpg

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.

Northern mountain ash and American mountain ash are closely related, the former having larger leaves, flowers and flower corymbs, as well as growing larger and often single-stemmed. It comes into flower about ten days later than American mountain ash. The end buds of the Northern mountain ash are almost black, very sticky, and hairy at the tip, all distinguishing it from S. aucuparia.Northern mountain ash should be considered as a group, within which individuals differ somewhat depending on their origin. All are apomictic, that is, they produce fertile seed without pollination; this means that all the off-spring from a single tree are identical.

 

Syndicate content