Standing tall on the crest of Ben Lomond Mountain are some of the loveliest oaks I’ve ever seen. I try not to play favorites as I walk through the mixed hardwood forest of San Vicente Redwoods, but I can't help but admire the enormous oaks that line the ridgetop.

I’ve always had a particular affinity for the Live Oak trees of the West Coast. Their grand canopies, gnarled branches, and evergreen leaves remind me of home, and I find myself missing them whenever I leave the coast or foothill ranges of California. My appreciation for Live Oaks grew when I began to study fungi many years back, and I uncovered the mycorrhizal relationships hidden within the forest. In my haste to find chanterelle, candy cap, and porcini mushrooms under the Live Oak trees each rainy season, I started to notice subtle differences, and similarities, in the trees that I thought I knew so well. Upon a closer inspection of my local Live Oaks, I only became more confused as to which one was which.

As far as I know, the Canyon Live Oak (Quercus chrysolepis) can be identified by its golden-capped acorn and a light brown underside to the leaves, whereas the Interior Live Oak (Quercus wislizeni) acorn is long and slender with smooth green/grey leaves, and the Coast Live Oak (Quercus agrifolia) has roundish cupped leaves with spines. Canyon and Interior oak leaves can also have spines though, and Coast acorns are sometimes long and slender. Interior leaves are flat, but then again, so are Canyon leaves? Wait, what the heck am I looking at!? Is this a Shreve Oak (Quercus parvula)?

Turns out oak tree identification can be quite challenging. In fact, arborists, botanists, and naturalists alike debate the identity of oak trees regularly. Oak trees are notorious for being highly variable in morphology, but to complicate things further, they also share a long history of introgression (the transfer of genetic material from one species into the gene pool of another). Along habitat edges, oak trees have been known to hybridize with one another, which combines the defining characteristics of the two parent trees. Given the variable landscapes and climates of California, hybrid oak trees are somewhat common here. This is certainly true with the oaks of San Vicente Redwoods.

I guess I may never know the identity of the trees I adore, but then again, I suppose I don’t have to. They’ll always be a sight to behold, a mystery to ponder, and most importantly, a vital part of California’s ecosystems. You’ll just have to see them for yourself!