Sorbus Aucuparia

Sorbus aucuparia (Rowan, European Rowan, Mountain-ash, or European mountain-ash), is a species of the genus Sorbus, native to most of Europe except for the far south, and northern Asia. In the south of its range in the Mediterranean region it is confined to high altitudes in mountains. It is the most widely available mountain-ash species in the United States.

Sometimes called "Mountain Ash", Sorbus is unrelated to the true Ash tree though the leaves are superficially similar.

It is a small to medium-sized deciduous tree typically growing to 8–10 m tall, more rarely 20 m, and exceptionally to 28 m. The bark is smooth, silvery grey of young trees, becoming scaly pale grey-brown and occasionally fissured on old trees. The shoots are green and variably hairy at first, becoming grey-brown and hairless; the buds are conspicuous, purple-brown, and often densely hairy. The leaves are pinnate, 10–22 cm long and 6-12 cm broad, with 9–19 (most often 13–15) leaflets; each leaflet is 3–7 cm long and 15–23 mm broad, with a coarsely serrated margin; they are variably hairy, particularly the petiole and leaf veins on the underside. The hermaphrodite flowers are produced in large terminal corymbs 8–15 cm diameter with up to 250 flowers, the individual flowers 1 cm diameter, with five creamy-white petals, and are insect pollinated. This occurs in May. The fruit is a small pome 6–9 mm (rarely up to 14 mm) diameter, green at first, ripening bright red in late summer, and containing up to eight (most commonly two) small seeds. It is diploid, with a chromosome count of 2n=34.

Four or five subspecies are recognised, for example:

• Sorbus aucuparia subsp. aucuparia. Temperate Europe and northwest Asia, south to central Spain, central Italy, and northernmost Greece, and east to the Ob and Irtysh rivers. Tree form; leaves and shoots hairy.
• Sorbus aucuparia subsp. fenenkiana T.Georgiev & Stoj. Bulgaria (endemic).
• Sorbus aucuparia subsp. glabrata (Wimm. & Grab.) Cajander. (syn. S. glabrata (Wimm. & Grab.) Hedl.). Subarctic regions, from Iceland, northernmost Scotland (Orkney, Shetland), northern Scandinavia, northwest Russia, and also locally at tree line in central Europe in the Alps and Carpathians. Shrubby; leaves and shoots less hairy.
• Sorbus aucuparia subsp. praemorsa (Guss.) Nyman. High altitudes in the Mediterranean region in France (Corsica) and Italy (Sicily and Calabria).
• Sorbus aucuparia subsp. sibirica (Hedl.) Krylov (syn. S. sibirica Hedl.). Temperate northern Asia, east of the Ob and Irtysh rivers. Tree form; leaves and shoots hairless.