Quercus douglasii blue oak

Quercus douglasii, Rogers House. Sairus Patel, 20 Mar 2020

Quercus douglasii leaves. From Trees of Stanford and Environs, by Ronald Bracewell

The second most common oak indigenous to the Dish area, blue oak – deciduous, with picturesquely twisted branches – is often assumed to be valley oak when seen from a distance, whether driving past the foothills or walking their trails, even by those with some familiarity. But it doesn’t attain the great height and size of that species, and its compact, dome-shaped crown can usually be recognized from afar by the trained eye.

The leaves appear as if someone had been asked to sketch – within a second – the rough outline of a leaf with wavy edges: irregular, each one quite different, the lobes shallow if present at all. They emerge a tender green in spring, harden through the season, and by late summer display the distinctive blue-green of their upper surface, the result of a waxy coating that helps them withstand the blistering heat of the Great Central Valley foothills.

Blue oak also dots the Outer Coast Ranges, including the foothills of our Santa Cruz Mountains, extending right into campus proper, especially West Campus, where venerable indigenous patriarchs still stand, drawn and identifiable on 1880s surveys of Stanford lands: a splendid tree in front of Dinkelspiel Auditorium, another behind Rogers House, a pair where Lomita Court leaves Lomita Drive, a group south of the barbecue facility at Lagunita, and numerous others in the parking lot north of the O’Donohue Farm and near Los Arboles Avenue.

Thousands of blue oak acorns planted since the mid-1980s in the Dish foothills and on campus by Magic have reportedly performed “abysmally,” in stark contrast to valley and coast live oak acorns. Where they survived, they have grown slowly. At Jasper Ridge blue oak saplings remain stunted in what is despairingly nicknamed the Bonsai Forest – a patch of sandstone substrate at the north end of exposed ridgetop grassland at the Preserve’s eastern end, just beside magnificent mature blue oak woodland. Deer likely browse the tender new growth. Across the species’ range, regeneration has languished for nearly a century, hindered by intensive grazing, invasive weeds, and drought – even though it is regarded as the most drought-tolerant of California’s tree-sized oaks.

Illustrations: Jasper Ridge plant photo archive.