Steve Young has updated the scientific plant names in Newcomb’s Wildflower Guide. It is available in a Google Document at: Newcombs Name Update.
It was first updated by Steve in 2007 and the 2010 changes are at the bottom of the document. If you like, you can contact the book’s publisher, Little, Brown and Company, and suggest they update the book. Their contact address is: publicity@littlebrown.com.