Sour cherry is an introduced tree from 5-10 meters high. The leaves are simple, alternate, and with elliptical to narrowly ovate blades, the base of the blade being rounded and the tip acutely pointed. The leaf surfaces are smooth on both surfaces and the margins are coarsely toothed as visible in the photo at right. The leaves range from 5-8 cm long.
The flowers tend to be somewhat pendant, and occur in clusters. Each of the 5 petals is white and of a suborbicular shape. The flowers are much larger (2.5-3.5 cm wide) than those of the other Prunus species listed here.
The sour cherry may be found in moist, open woods.
The sour cherry is an escaped, cultivated plant, found occasionally west of the Cascades.
In the Columbia River Gorge, it may be found at low elevations from the west end of the gorge to as far east as Starvation Creek State Park.
Note: The photos shown here might be Prunus avium. I'll have to go out with a current taxonomic key to verify what these common small trees are in the western Gorge.