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Highway 128’s Botanical Mystery

After driving back roads and living off the beaten path for 50 years I consider myself fairly knowledgeable about our local natural world. When I see something growing along the road that truly looks out of place my mind goes “Hmmm…How did that get there?”

Having explored Sierra forests in the past I recognize an Incense Cedar when I see one. East of Boonville on Highway 128 where it descends into the Robinson Creek drainage is a hillside of shiny serpentine rock with Incense Cedar growing in it. What’s weird about that? Those trees are usually found several hundred miles east on the western slope of the Sierra between 3,000’ and 6,000’ elevation. What are they doing on a lower elevation in a warmer drier climate along Highway 128?

In the Sierra these trees grow quite large in moist canyons, five or six feet thick and 150’ tall with bark six inches thick. Their crushed aromatic leaves have a pungent odor. In the Sierra they grow beautifully. Along Highway 128 they look like they are lucky to be alive. Ring counts on the largest of these trees showed them to be 100 years old in the 1970’s.

OK folks…where did they come from? Was a pioneer who had been gold mining in the Sierra carrying tiny pine cones in his pocket and acting like Johnny Appleseed and spreading seed wherever he went as he came west. Did a pioneer mother tend a seedling in a pot until she could plant it on a homestead in Mendocino County because she liked the smell? If any reader has a story on their introduction to the flora of the county I’d love to hear it. Contact me through the AVA website.

The most evident factor for their survival may be the dirt under their roots. Incense Cedars grow on rocky serpentine soils often greenish in color as seen in the road cut there and few other trees or shrubs grow there. The soil contains high magnesium and low calcium in content and it’s toxic to a lot of vegetation. In areas where serpentine content is lower in the soil other plant life dominates and Incense Cedars are scarce or absent.

Occupying an ecological niche no other vegetation wants they grow today and motorists can see them. This botanical mystery came to my attention in the “Mendocino Medicine and Gazetteer” volume 22 June 1987 by Dr. Richard White reporting the research of Pacific Union College students in 1977 who studied these trees.

Dr. Richard White was a man of eclectic interests both in medicine and the natural world who raised a family on the coast in the 1980’s and 90’s and practiced medicine in many locations in the county. I’m researching and taking notes from six bound volumes of his publications on loan from Deborah White in Ukiah. Dr. White passed away in 2005 but left a wealth of information on the natural world of Mendocino County in his writings which will inspire future stories of mine.


  1. Douglas Coulter December 5, 2020

    Millions of tons of Sierra Soil clogged the Sacramento River from hydraulic digging. That is the only reason hydraulic mining was banned. Perhaps a few trainloads of this free fill dirt made it north from as close as Petaluma.
    Serpentine contains asbestos but it does not seem tied to lung issues in low exposure. Miners and the rock crushers did have problems.

  2. Chris Seides December 5, 2020

    I planted two cedar seedlings from the Sierra at my house in Fort Bragg and they are thriving having grown from 6 inches to over 15 feet tall in about 10 years. This is about one mile inland.

  3. Wayne Doe December 5, 2020

    There is another stand of Incense Cedar near Alder springs & Keller lake in the Mendocino National Forest.
    Not sure how they got there.

  4. George Hollister December 5, 2020

    My guess is Indians brought the incense cedar here, many moons ago, and the reasons have been long lost to history. Using the bark as a source of fiber is a possibility. The sugar pine near the coast is also out of place, and could have gotten to where it is the same way.

  5. Brian December 6, 2020

    I could be wrong, but I believe there’s a grove of giant incense cedar above Jack Peter’s Gulch also.

  6. David Weitzman December 11, 2020

    There’s is a large stand of incense cedar near me, at the intersection of the Mina and Hulls Valley Roads about ten miles north of Covelo. The elevation seems right for them, about 2,800 feet, but, still, they are very unusual for these parts. Years ago I found seedlings in the gravel along the road, transplanted them to near my house, and they have flourished.

  7. Wayne Doe December 12, 2020

    Just remebered that my friend owned a piece of land on the Old Bower ranch which is on Mt. Anthony & in one step draw there was a single Incense Cedar tree. That area burned twice since he sold his land. I wonder if it survived.

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