Sorbus aucuparia aka Rowan

Sorbus aucuparia is known as rowan or European mountain ash. This deciduous tree belongs to the rose family, not true ashes. Its native range covers Europe and parts of Asia. It is native to Britain and Ireland as well. Garden trees reach about 20–40 feet [6–12 metres] tall. The RHS reports that some grow beyond 39 feet [12 metres]. Spread reaches about 26 feet [8 metres].

Young trees have an upright, oval crown that rounds with age. A short trunk can split into several main stems. Branches rise and spread out from the trunk. Young bark is pale gray, with small white air pores. Older bark darkens and develops cracks and small scales. The alternate, pinnate leaves have nine to fifteen leaflets. Their toothed edges become smooth near the base. Green leaves turn yellow, orange, red, or purple in autumn. Fall color can vary from tree to tree.

White flowers open in flat clusters during May or late spring. Their smell can be unpleasant, though the blooms add spring interest. Small orange-red pomes follow, ripening in late summer and early autumn. These berry-like fruits grow in clusters at branch tips. Birds eat them, making rowan useful in wildlife gardens. Gardeners also grow it as a lawn specimen or small shade tree. It suits cottage gardens and woodland settings in cool climates. Its wind resistance gives it value in shelter plantings.

Rowan grows best with full sun and moist, well-drained soil. It also tolerates some shade, but sun helps fruit production. Acid or neutral soil suits it, with humus and moderate fertility. Avoid compacted ground and hot, dry sites. Heat and humid summers can limit growth and tree health. Sources differ on how well it handles air pollution. Its listed hardiness spans USDA zones 3–7 and UK rating H6. Growth is moderate, and garden trees can be short-lived.

Fireblight can damage shoots, while scab can cause leaf loss. Cankers, rust, mildew, and honey fungus are other risks. Aphids, scales, sawflies, mites, and borers may attack it. Stress makes trees more prone to borers and cankers. Sources describe fruit uses in jams, drinks, and preserves. Large amounts of raw fruit can cause vomiting or stomach upset. Young leaves and seeds contain compounds that can release cyanide. The RHS warns against eating ornamental fruit, including for pets. Food uses therefore do not mean all parts are safe.