Almost incandescent in the soft light of an overcast sky, the
remarkable color of this scrub oak apple gall contrasts sharply
with the muted greens, grays and browns of the surrounding
chaparral. The gall forms in response to the larvae of the
California gall wasp. The gall protects the developing larvae,
as well as providing it a source of food. On the right side of
the gall there appears to be a "sun print" of an oak leaf in the
red color, where a nearby leaf may have shielded the surface
from sunlight. From today's run on the Backbone Trail in the
Santa Monica Mountains, near Saddle Peak.