Frangula rubra

Frangula rubra (syn. "Rhamnus rubra") is a species of flowering plant in the buckthorn family known by the common names red buckthorn and Sierra coffeeberry. 
Distribution.
It is native to the mountains and plateau areas of northern and eastern California and western Nevada, including the Sierra Nevada and Klamath Mountains, where it grows in many habitat types, including forests, chaparral, and sagebrush.
Description.
"Frangula rubra" is a spreading shrub approaching two meters in maximum height, its bark red or gray. The thin, deciduous leaves are generally oval in shape, green to grayish in color, and up to 8 centimeters long. The edges are smooth or faintly toothed. The inflorescence is an umbel of up to 15 flowers with five pointed sepals opening into a starlike shape and five smaller, greenish petals. The fruit is a drupe which ripens to black. It measures just over a centimeter long and contains 2 seeds.