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IOS Tour of California, Part 1: Northern California
My decision to join the International Oak Society Tour of California came about when exploring the far north of California in the autumn of 2023. A conifer fan by choice, I had spent a glorious three weeks exploring the oldest, largest, and tallest trees on earth—a forester’s and personal lifelong dream. However, life is not all conifers and during my tree twitching1 I ticked off quite a few other species, amongst these several oaks. The Quercus kelloggii, Q. lobata, Notholithocarpus densiflorus, and Q. agrifolia were straight forward, as I had seen these in our own collections. But the vast array of evergreen, often spikey, usually scrubby “live” oaks left me, if I am honest, totally confused. Add in the tendency for frequent hybridization and I was totally lost. What I needed was expert help.
On returning to the UK from my travels, I was reading the International Oak Society newsletter and realized annoyingly that the Society had been exploring oaks based in Redding, California the day after I passed that way on my journey to the coast. A missed opportunity if ever there was one. When I saw the proposal to tour California in 2024, I leapt at it. So here we are.
Our Tour started with a get-together at the UC Davis Arboretum. We were met and led on a fabulous walk around Shields Oak Grove by Emily Griswold, Director of Horticulture. This was followed by a getting-to-know-you soiree. I will add at this point I am normally a solo traveller and had some trepidation about joining a group tour. I need not have worried as the passion for trees crosses many genera, and I found myself engaged in “oak” talk and, dare I say it, already in danger of becoming a novice querciphile.
Day one (September 14th) of the official Tour took us to Walker Ridge in North Coast Ranges where we turned off Highway 20 onto, oddly enough, the Walker Ridge Road. We made it about 200 m to our first stop and my official first oak, Q. douglasii. These blue oaks lived up to their name and I was already disabused that all the California oaks are shrubby and spiky! A short drive later and we became very aware of the results of a forest fire. For a foreigner not used to the scale of these burns it looked devastating. But after a closer look, lots of discussion, and some education, I soon realized that these are part of normal natural processes. All around were signs of regenerating forest. This included Hesperocyparis sargentii (another conifer tick) and many oaks resprouting from the base. These trees have evolved with fire, and it was wonderful to see how nature can turn around what initially looks like a disaster. I soon realized this would be a common theme on our travels. The day proceeded with a session of frequent stops, lots of questions, more than a few photos, and a growing list of species that included Q. wislizeni var. frutescens with lovely clusters of acorns, Q. palmeri, Q. lobata, and a few supposed hybrids with indeterminate parentage that sometimes led to long and interesting discussion on what the hybrid could be. This turned out to be another common theme.
Day two (September 15th) was a drive north with a stop off Highway 162 at the Round Valley overlook. Here the first oak of the day was Q. durata, quite a shrubby species growing in this rather exposed site. From here we made our way to the Mendocino National Forest along the Mendocino Pass Road. There was plenty to see with some fine Q. agrifolia and my first acorns of Q. chrysolepis, which lived up to one common name, the golden cup oak: they are gorgeous, and I think I’m in love! One other standout tree was a very furry-leaved Q. kelloggii, an attractive plant that would make a fine specimen in any collection. We completed the day with another first, the conifer Pinus attenuata, the knob-cone pine. I would see more later in our travels.
Day three (September 16th) took us to Tahoe National Forest accessed along the Mosquito Ridge Road. I was particularly looking forward to this day as we were heading into the high conifer forests. With an early stop to look at some fine Q. chrysolepis with acorns even prettier than at the last stop, the cups covered in downy golden hairs. We were greeted further up the road by evidence of more, recent forest fires. What stood out again was the regeneration taking place, particularly in a grove of knobcone pine. It was frequent and widespread and demonstrated how fire is needed by some species to regenerate. In this case heat from the fire required to open the serotinous cones. From here we traveled to the Big Trees Picnic Site, which, as it says, is amongst the conifer forests dominated by sugar pine (Pinus lambertiana), western white pine (Pinus monticola), Douglas-fir (Pseudotsuga menziesii), Incense cedar (Calocedrus decurrens), ponderosa pine (Pinus ponderosa), and the most northerly remnant groves of giant redwood (Sequoiadendron giganteum): I felt at home.
There were, however, three quite curious and unusual members of the oak “family” present: Q. vacciniifolia, a short shrubby understory tree that is easy to miss; Notholithocarpus densiflorus, with the acorn perched precariously atop the bristly prickled cup; and the quirky and even more prickly Chrysolepis sempervirens, the fruit so reminiscent of sweet chestnut (Castanea sativa)—the true native chestnut having nearly been wiped out by disease in the US.
With a group picture next to the giant redwood to finish the day we headed home ready to travel the long way south to Los Angeles the following day. The real “scrub oak” journey was about to start, and I was very much looking forward to it. Oh! and I’m still sorting through my 2,500 photos and wondering what the total for the group was.
Read the report of the second part of the Tour here.
1 In British slang, a twitcher is an enthusiastic bird watcher.
Photos © Chris Reynolds, unless specified
Acknowledgments
The IOS is grateful to Sean Hogan and Preston Pew for leading this Tour and to the following institutions for their generous support:
