Just as my family tree in the San Gabriel Valley has changed over the generations, the various native plant communities within the same area have also been compromised. None more apparent than Southern Oak Woodland. This community includes principal trees such as the Engelmann Oak (Quercus engelmannii), Coast Live Oak (Quercus agrifolia), Black Walnut (Juglans californica). Of those three, the Engelmann Oak has suffered the greatest impact, but it has the treasured opportunity to be recognized for its beauty and unique distinction to San Gabriel Valley.
Once found throughout the San Gabriel Valley, the Engelmann Oak has most recently suffered greatly from insect and fungal pathogen damage, followed by poor cultural practices like overwatering. Urbanization and stress caused by drought and fires have also posed a greater threat to these legacy trees. The population has also been afflicted by a lack of availability in the trade until now. I was so inspired by seeing beautiful Engelmann Oaks at The Huntington Botanical Garden, Los Angeles County Arboretum, and this year’s Theodore Payne Annual Native Plant Tour, that I wanted to learn even more about its roots within the Southern Oak Woodland native plant community.
For some unknown reason, my family and I have always enjoyed learning about our ancestors. Maybe it’s because we are all scientifically and oddly inquisitive – a family of nerds right at home in the land of JPL, CalTech and SpaceX. And we are all also surprisingly of sturdy stock like an oak tree.
My late grandfather respected the oak so much that he asked that the California Live Oak (Quercus agrifolia) be etched onto his tombstone. He also planted a White Oak (Quercus robur) close to his home. Exploring the genealogy of the Genus – Quercus and its relationships has helped me learn more about my own roots within Southern California.
Sadly, you can’t just go to Ancestors.com for answers about the roots of an actual tree. You need to go to a library of natural history. So off I went on a Saturday to the Los Angeles Arboretum. I culled the stacks and found a manuscript written by Bruce M. Pavlik titled, A Natural History of Southern California Oaks, with Emphasis on Those Occurring within the District. After reading it, I hiked around the park for further inspiration about the Southern Oak Woodland native plant community.
Published in 1976, Pavlik’s manuscript shared many of the same concerns about the California native oaks within the Los Angeles district that are threatened today. Most significantly, he called for the protection of Engelmannn Oaks in response to the rapid urbanization of the San Gabriel Valley in the 1970s. Prior to development, Engelmann Oaks were only threatened by horse and cattle grazing, which destroyed any opportunity for seedlings to flourish into trees around the valley floor. The young trees survived only along the ridge lines, because it was too dangerous for cattle and horses to graze upon their foliage.
Within its family tree/taxonomy, the Genus amongst California native oaks resides in the order of Fagales, consisting of the families Betulaceae and Fagaceae. Birch (Betula), Alders (Alnus), and Hazelnut (Corylus) reside in the family of Betulaceae, and they are the closest of relatives of California native oaks. Within the family Fagaceae are the Genus of oaks and their relatives, such as Chrysolepis, Quercus, and Lithocarpus.
The mid-sized, evergreen Engelmann Oak has the distinct characteristics of a California Live Oak, yet, instead of green leaves that are slightly serrated, it has vibrant blue-grayish-green leaves that are rather long in length and relatively unserrated edges. The tree’s acorns have a slightly hairy underside on the cap. The acorns of this particular tree were harvested last by the native peoples for food, as acorns from other species like the Valley Oak (Quercus lobata) and Coastal Live Oak (Quercus agrifolia) tasted better or offered more nutrients. Unfortunately for the Engelmann Oak, it was most preferred by the locals as firewood, as its wood seemed to burn the longest of all local hardwood trees.
These impressive trees are rarely found north of Pasadena, and only along the northern side of a foothill, generally in thick stands within shallow soil supporting aromatic plants White Sage (Salvia apiana), California Buckwheat (Eriogonum fasciculatum), and California Sagebrush (Artemisia californica). Along the valley floors and around mesas, Engelmann Oaks were surrounded by California Poppies (Eschscholzia californica) and Purple Needle Grass (Stipa pulchra) growing around the base of these majestic trees. I bet this was a very beautiful sight my ancestors enjoyed living in San Marino, Sierra Madre, and Monrovia prior to the mid-1850s. Engelmann Oaks were once spotted along a 50 mile wide beltway from Pasadena, all the way to Mexico, always at least 15 to 20 feet from the nearest coastline.
The Engelmann Oak shares the growth rate of the Coastal Live Oak, growing about 8’ in 5 years. Of all the oaks, the Valley Oak grows the fastest at 15’ in 5 years. Lucky for us, the Engelmann Oak is now available to purchase from a local tree nursery, and it can still be found around growing within neighborhoods of Duarte, Pasadena, Azusa, and Glendora. The Los Angeles Arboretum and the Huntington Botanical Garden have a few that you can see, touch, study, and enjoy. I really found walking through the tree’s dense pillow of foliage debris lining the way toward a bench underneath the massive tree at the LA Arboretum unlike anything I have ever done in Los Angeles.
I went onto Google Earth to continue searching for more EEngelmann Oaks within the area, looking out for a particular hue that helps identify the trees from others. The Engelmann Oaks are fairly easy to spot based upon their color of foliage depicted on Google Earth. It was like finding members of your family tree that you did not know existed. The activity made me want to look for even more Engelmann Oaks and determine how to enable further protection of them or build more colonies of these special trees unique to San Gabriel Valley.
Engelmann Oaks can help make the San Gabriel Valley a better and more beautiful community, while strengthening the native plant community of the Southern Oak Woodland. So hopefully everything I’ve shared above will compel others to appreciate and plant some of these wondrous native oaks.