Lost and Found in San Francisco

In an all too common story, limited populations of plants continue to end up lost to urban development. There were once three populations of the Franciscan Manzanita (Arctostaphylos franciscana) within the city of San Francisco—in two cemeteries and at Mt. Davidson, the highest natural point in the city that is named in honor of George Davidson, a charter member of the Sierra Club. But San Francisco was a fast-developing city. In 1911, Mt. Davidson was purchased by A.S. Baldwin who had plans to develop many new neighborhoods in the area. This was bad news for these three populations of Arctostaphylos franciscana. By 1947, it seems the last in-the-wild plant at Laurel Hill Cemetery on Lone Mountain was lost to commercial and residential development. There were cuttings from this plant, however, that were preserved. The plants from those cuttings survived in botanical gardens. Then in 2009, there was a discovery of an individual manzanita plant found more than 60 years after it was thought to be extinct in the wild. A single plant was found on the Presidio near Doyle Drive.

The Manzanita, endemic to San Francisco, is a low evergreen shrub that has been confused with another rare plant, the Raven’s or Presidio Manzanita, A. Montana ssp. Ravenii. The two have different ploidy levels (the number of chromosomes occurring in the nucleus of a cell), an indication that the two most likely could not interbreed even with their similarities. The story of how Presidio biologists are attempting to find a mate for this rare Manzanita can be found here.

Stay tuned as the search continues.

Information from: “Emergency Petition to List the San Francisco Manzanita (Arctostaphylos franciscana) as an Endangered Species,” Wild Equity Institute, December 14, 2009.

“Sex and shrubbery: Presidio biologists seek mates for SF’s loneliest plant,” by Steve Rubenstein, San Francisco Chronicle, February 23, 2018.