The Coast Live Oak (Quercus agrifolia), dark green, keeps its leaves all year. Valley Oak (Quercus lobata) loses its leaves each fall. Valley Oaks are "winter deciduous", losing leaves in response to season and light. [ The Blue Oak id "drought deciduous" and well-adapted to drought.] These Valley Oaks are just getting new spring leaves -- one in front is ahead of the others in this process. A little Artemesia chaparral is on the right. The old brown grass in the foreground testifies to the absence of cattle on Jasper Ridge.