California yerba santa (Eriodictyon californicum) is a chaparral shrub of western California and south western Oregon. Its leaves are rich sources of natural flavonoids. Leaves collected from wild stands in general contain the flavonoids homoeriodictyol, eriodictyol, hesperetin, and smaller amounts of other flavonoids. These flavonoids are of possible medical value and are subjects of intensive medical research. California yerba santa leaves containing substantial amounts of the flavonoid sterubin would be of special interest due to sterubin’s potential activity against the enzymatic and inflammatory pathways leading to Alzheimer’s disease in humans as discovered by the Salk Institute of La Jolla, California. We collected leaf samples from SW Oregon through California over the range of plant distribution. Not all areas were sampled. Total flavonoid content in excess of 10 percent of leaf dry weight were common. Leaves with sterubin content were relatively rare. Sterubin content of several samples exceeded 5 percent of leaf dry weight.
