Martha Plimpton, who is a well known stage actress and former girlfriend of River Phoenix, has been introduced into the cast of Grey’s Anatomy as the mother of a young patient.

Her role is rumored to be for five to six episodes, which will become a major plot arc in Season Six.

Martha Plimpton is also rumored to be playing Helen Craig in the movie ‘Remember Me’ with Robert Pattinson and Emilie de Ravin. Remember Me is set to be released in February, 2010.