Even though very local and scarce at the UC Hopland Research & Extension Center, the flowering shrub called Red osier Dogwood (Cornus sericea L. ssp. sericea) is hard to miss with its winter display of red bark.   This plant goes by other common names such as American dogwood, creek dogwood, red-rood, red willow, and redstem dogwood. 

It is a native to northern and western North America, and is found in the extreme north part of California and a portion of the central Sierras .... but interestingly occurs sparsely throughout the state in isolated pockets of riparian or wetland habitat as far south as San Diego County.

Red osier dogwood can be started easily from cuttings, is found in the horticulture trade, and the cultivar "Flaviramea" has won awards for the bright red color during the dormant period.  In damp soils it spreads easily by underground stolons to form dense thickets ... and this trait resulted in the past synonymous name of Cornus stolonifera.  It can cause mild dermatitus in some.