Jasper Ridge contains many ecosystems and many landscapes. One tree stands out in this collection: the Valley Oak (Quercus lobata). Although Valley Oaks may not be the most common oaks at Jasper Ridge (I suspect this title goes to the California Live Oak), to me, they are the most iconic. Many Valley Oaks grow alone, surrounded by grassland. Their bare shapes in winter are this photographer's dream. Their new green leaves in spring delight the heart. Summer brings a dark-green, full canopy.
In fact, many of these images include one single Valley Oak, labeled the "Lonely Valley Oak", in the grassland, near the serpentine, on the ridge.
The Valley Oak is in the White Oak evolutionary lineage. Other members of this lineage at Jasper Ridge are the Blue Oak (Q. douglasii) -- found in a single-aged stand along Road F west of the Serpentine, near Trail 4 -- and its hybrid with the Valley Oak; and the Leather Oak (Q. durata var. durata) and its hybrid with the Blue Oak. There is also a hybrid Scrub Oak (Q. berberidifolio) and Valley Oak. Oaks hybridize readily with other members of the same evolutionary lineage, and not at all with members of another lineage.
The common Coast Live Oak (Q. agrifolia) and the rare Black Oak (Q. kelloggii) belong to a separate lineage, the Red Oak Lineage, and the Jasper Ridge Vascular Plant List says that their hybrid is also found at Jasper Ridge. (The Black Oak, rare in Jasper Ridge, is more common up higher in the foothills, and in the Sierras including Yosemite Valley, but it is not often the dominant tree.)
Other trees and other ecosystems can also be found in this collection, if you look hard enough. More recent images can be found in "A Day at a Time".