Oregon ash Fraxinus latifolia

Oregon ash is a deciduous tree in the olive family (Oleaceae).  It is native to the Pacific coast of North America. The species epithet means “wide leaves [leaflets],” and Oregan ash has wider leaflets than most other ash species. 

Oregon ash is found growing on deep, poorly drained clays or silty clay loams rich in humus. It will also grow on sandy, rocky, and gravelly soils along waterways or areas with seasonal flooding and prefers a pH of 5 to 7. It will grow in sun to part shade and can be used as a shade tree given the right conditions. It is also used to reclaim wet areas and meadows.

This tree grows 65 to 80 feet tall and can be very long-lived, up to 250 years. It grows fast as a young tree but slows down with maturity. The crown is broad and rounded in uncrowded conditions. It is found growing along waterways, bottomlands and other damp to wet sites. It prefers climates with cool and humid summers and winters that are usually mild. Dry conditions will cause stunting of growth, loss of leaves and allow for diseases to take hold. Being dioecious, it needs both male and female trees to produce fruits and seeds.

Insects, Diseases, and Other Plant Problems: A variety of fungi cause leaf spot and powdery mildew. A heart rot can cause an extensive defect in older trees. See potential insect and disease problem factsheets to the left.

VIDEO created by Ryan Contreras for “Landscape Plant Materials I:  Deciduous Hardwoods and Conifers or Landscape Plant Materials II:  Spring Flowering Trees and Shrubs” a plant identification course offered by the Department of Horticulture at Oregon State University