[Wikipedia] Rarity, Range, Threats: Phacelia argentea is a rare species of phacelia known by the common names sand dune phacelia and silvery phacelia. It is native to the coastline of southwestern Oregon and far northwestern California..It is the only phacelia species endemic to coastal sand dune habitat, an ecosystem which is altered and declining in the area. A main threat to this rare species is the presence of the introduced non-native European beachgrass (Ammophila arenaria), which was once planted to stabilize the sand dunes and now dominates. (link added by Mary Ann Machi)