The most common oak at the trailer's elevation is the California Black Oak, but in places the evergreen Canyon Live Oak, QUERCUS CHRYSOLEPIS, dominates, and when that tree's acorns lie on the trail it seems a shame to walk on them. That's because its acorns' cups are a beautifully bright, golden hue, as gold as the crown on a Walt Disney lion, unlike any acorn cup I've ever seen. Walking over ground covered with such pretty acorns you feel like you're in an enchanted grove. On the Internet I can't find pictures of cups as vibrantly golden as ours, so I wonder if ours are unusually bright. You can get a hint of what they look like at http://www.coestatepark.com/quercus_chrysolepis.htm.
Local native people used to eat Canyon Live Oak acorns despite their high tannin content. The traditional manner of removing the tannin was to bury the acorns in boggy ground over winter. The germinating seed were dug up in the spring after most of the astringency had been neutralized. Another approach was to put them in a stream and let running water leach out the tannin, a process that might take weeks. Once the tannin was removed, the acorns were dried and ground into a powder used as thickening in stews, and mixed with grains for making a heavy, scratchy bread. Roasted acorns could be ground and the resulting powder brewed to make a drink something like coffee.
One curious thing about these Canyon Live Oaks is that the leaves of young branches are small and spiny- margined like holly leaves, but on mature trees the spines are missing. On some branches you can find both leaf types. The leaves are so variable that often they are confused with those of other species. However, there's one feature that separates Canyon Live Oak leaves from all others in the area -- at least when young, blade surfaces are covered with "multiradiate trichomes," or star-shaped hairs.
In parts of El Dorado National Forest you're nearly always in sight of one or more pretty California Sister butterflies, ADELPHA BREDOWII. In this area the Canyon Live Oak is the main host for that butterfly's caterpillars. You can see pretty a California Sister at http://www.npwrc.usgs.gov/resource/distr/lepid/bflyusa/usa/2.htm.
Unfortunately this wonderful tree has a fairly limited distribution, mostly in California and part of Arizona. Its distribution map can be studied at http://www.efloras.org/object_page.aspx?object_id=6752&flora_id=1.