Too dry for redwood sorrel?

Dry redwood sorrel shows signs of drought stress at Armstrong Redwoods.
Dry redwood sorrel shows signs of drought stress at Armstrong Redwoods.

I recently walked with a childhood friend through Armstrong Redwoods State Natural Reserve, one of the only old coast redwood forests left in Sonoma County. It certainly felt like fall, with the sunlight low in the sky as midday approached. Along the trail I saw patches of redwood sorrel, the common herbaceous plant that looks so much like clover.

This unassuming species has always appeared hardy to me as it toughs it out in the shadow of the redwoods, but on this walk I saw signs of stress. Patches of redwood sorrel had curling leaves that appeared crispy. Not all the sorrel was affected, but I was surprised to see such sad sorrel in many places. We’ve had such a dry year in California and in the redwood forest, it’s been way to many months since sustained rainfall soaked the woods. I suspect this has left redwood sorrel dehydrated and without enough water to avoid the warm sunlight that filters down through the forest canopy.

Typically, sorrel avoids the sun by intentionally lowering its leaflets like a folding umbrella to prevent heatstroke when bright sun flecks pass across the forest floor. This sun-avoidance strategy usually protects the plant well, but is only effective when the plant is well hydrated. Instead of sun salutations, the Armstrong redwood sorrel has simply dried out and curled up. Hopefully the rains will come soon and the lovely redwood sorrel will recover. Everybody do a rain dance!

For another observation about of how redwood sorrel reacts to the weather, read Seen Sorrel Cry?

About the author

Emily Burns, the League’s former Director of Science, led the research program that includes the Redwoods and Climate Change Initiative. She holds a PhD in Integrative Biology on the impacts of fog on coast redwood forest flora from the University of California, Berkeley.

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3 Responses to “Too dry for redwood sorrel?”

  1. Anna Hansen

    I just had to say this cause in the least expected places a simple jester of hope and patience is a sweet reward.

    I have a degree in forestry and many years ago I remember those junior logging conferences, those dendrology classes… One thing I learned that with a little time native species will take the opportunity to return. Plant seed that are buried under years of duff then nourished by the ashes of fire can sprout and plant pushed out by invasive species return when those plants have been stripped away.
    Wow. I have what I think is super exciting news. In 2017 we bought an 1925 cabin on the Russian River, Fitch Mountain. What a mess. Pretty much the entire lot was covered with ivy. (Hate the stuff) the first season my wonderful helper dug down and pulled the stuff out by the roots. Instead of landscaping, we’ve let the natives return. Literally one by one there are seedling, toyon snowberry, Indian soap plant it’s amazing. But the plant which took all by surprise was the redwood sorrel. Last year it reappeared this year it’s cascading down the retaining walls… and heading down the bank to reclaim it rightful place under the small grove of redwoods along the river. I guess the lesson the is patience do back off on those nasties. It well worth the wait!

  2. Emily Burns

    Teresa, you’re asking great questions! One thing that has puzzled me for years is why some coast redwood forests don’t have redwood sorrel or only have a little. We think that sorrel is fairly sensitive to disturbance, so places that are trampled now or were trampled in the past are tricky for sorrel to thrive. It’s a very shallowly rooted plant with roots growing above the soil and intertwined in the fallen leaves on the forest floor. Since there is a patch of sorrel that is hanging on near your family cabin, that’s a great sign and I imagine it will spread over time if the reason it’s limited now is because of past land use. Minimizing compaction near the plants is probably the best thing you can do.

  3. Teresa

    We are fortunate enough to have a rickety 1940s family cabin in the Mendocino County redwoods, and I noticed this summer that the sorrel was quite sparse up there.

    How do you propagate it/help it spread/survive? Can you buy redwood sorrel somewhere and plant it? Are there sorrel seeds? How do you make it happy and encourage it to bounce back?

    I know it’s really a wild forest… …but I’d like to help our little patch of it stay healthy as much as possible.



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