Sorbus americana aka Mountain Ash

Sorbus americana, or American mountain ash, belongs to the rose family. This small tree sheds its leaves each fall. Its native range runs from Newfoundland south to Georgia. It grows in woods, near swamps, and on rocky hillsides. In North Carolina, it grows chiefly in the mountains. It can also take the form of a shrub. Growth is slow, and pests and disease can shorten its life.

Garden trees often reach 15–30 feet [4.6–9.1 metres] tall and wide. Size estimates vary between sources. RHS gives heights of 26–39 feet [8–12 metres]. It lists widths of 13–26 feet [4–8 metres]. Virginia Tech reports trees reaching 40 feet [12.2 metres]. The crown widens with age and takes a rounded shape. Young gray bark has many small pores called lenticels. Older bark cracks and forms scaly patches. Young shoots lose their down and become reddish brown. Dark red buds bear fine hairs.

The pinnate leaves have toothed leaflets with pale undersides. New leaves start downy, then lose their hairs. Fall brings yellow or red leaf color. Small white flowers form broad, flat clusters called corymbs. Sources place bloom between May and July. Bees visit the flowers. Orange-red pomes ripen in late summer and fall. These small, berry-like fruits may stay on branches into winter. Birds and mammals eat them. Moose and white-tailed deer also browse the tree.

Give this tree moist, rich soil that drains well. It favors acid soil, though RHS also accepts neutral soil. Full sun suits it, but it tolerates some shade. Cool climates suit it better than hot, humid summers. Chicago lists USDA zones 2–8; NC State lists zones 2–6. RHS rates it H6 for UK conditions. It serves as a lawn specimen or small shade tree. Native gardens, slopes, and natural plantings are other supported uses. Its flowers, fruit, and fall leaves provide seasonal interest.

Fireblight can cause severe damage, while scab can strip leaves. Cankers, rust, crown gall, and powdery mildew may occur. Aphids, borers, scale insects, mites, and sawfly larvae can attack. Stressed trees face greater risk from borers and cankers. Food guidance differs: NC State describes jelly made from fruit. PFAF records cooked uses and warns about tannins in raw fruit. It also notes that seeds may contain hydrogen cyanide. RHS warns against eating the fruit and flags pet risks.