Cascade Mountain Ash, Cascade Mountain-ash, Greene's Mountain Ash, Rocky Mt. Mountain Ash: Sorbus scopulina (Synonyms: Pyrus scopulina, Sorbus cascadensis, Sorbus scopulina var. cascadensis, Sorbus scopulina var. scopulina)

The photo above shows cascade mountain ash in bloom along the road to the old ski area at the base of Simcoe Butte, several miles northwest of Satus Pass in south-central Washington.........June 16, 2007. The number of leaflets per leaf on this species varies from 9-13 and each leaflet tends to be toothed along most of the margin.

Cascade mountain ash is also known as Western or Greene's Mountain Ash. It is an erect, several-stemmed deciduous shrub or small tree from 1-4 meters in height. The twigs are round, 2-4 mm in diameter and brown in coloration, with wrinkled and slightly short hairy surfaces that have vertical, white or orange raised areas. The winter buds are dark brown, glandular, and covered with white hairs.

The leaves are alternate on the stems. Individual leaves are pinnately compound, with 9-13 leaflets. The leaflets are narrowly oblong or oblong-elliptic to oblong-lanceolate in shape, and range from 3-7 cm long and usually less than 1/3 as wide. The leaflets are serrate margined much of their circumference. The tips of the leaflets may be acutely pointed, or more commonly blunt with a short point at the tip.

The inflorescence is a flat-topped cluster or corymb of 70-200 small white flowers. The calyx of each flower is covered with white hairs. Each of the 5 petals is oval in shape and from 5-6 mm long. The fruits are small (1 cm long) and glossy orange to scarlet in color. The fruits are found in clusters.

The fruits are an important food source for both birds and small mammals during the winter months. The western species of mountain ash have not been as extensively used for horticultural purposes as the eastern species, although Cascade mt. ash is well suited for such purposes.

Cascade mountain ash is found in upland woods from the foothills to subalpine or alpine slopes.

Cascade mountain ash may be found from Alaska south to northern California, and east to Alberta, the Dakotas, and New Mexico. In the Pacific Northwest, it is found on both sides of the Cascades, but is most common east of the Cascade crest.

Close-up sideview of the inflorescence of cascade mountain ash along the road to the old ski area at the base of Simcoe Butte, several miles northwest of Satus Pass in south-central Washington.........June 16, 2007.

Close-up of a flower of cascade mountain ash as seen on Wedge Mt., Wenatchee National Forest.........June 8, 2009.

Close-up views of cascade mountain ash as seen on Wedge Mountain, Wenatchee National Forest.........June 8, 2009.

Cascade mountain ash as seen blooming (left) along the primitive road into the Celebration Mine at the west side of Baldy Mt., Strawberry Mt. Wilderness.........July 2, 2016. The photo at right shows the colorful fall foliage of Cascade mountain ash on the east side of and below the summit of Spanish Peak, Ochoco National Park.......September 25, 2016.

Cascade mountain ash blooming at left along the North Fork Catherine Creek Trail #1905 about a mile above the trailhead, Wallowa-Whitman National Forest.......June 12, 2018. The photo at right shows Cascade mountain ash blooming at Teal Springs Campground, Umatilla National Forest.....June 16, 2023.