Bloodtwig dogwood (Cornus sanguinea) is a Eurasian species that has become established along the Boise River Greenbelt in central Boise and Garden City.  In some places, notably next to Boise State University, it is actually more common than its native look-alike, red-osier dogwood (Cornus sericea).  The most unequivocal diagnostic character is berry color:  black in bloodtwig dogwood, white or pale bluish in red-osier dogwood.  The leaves are also sufficiently different to aid in identification, with those of bloodtwig dogwood having fewer veins on average and a blunter apex.  Care should be taken when selecting plants to propagate for restoration purposes!