HIKES AND NATURE WALKS IN THE SAN GABRIELS
Walks on the Wild Side, Fall-Winter, 2008-9
December 3, 2008
Hacienda Hills, Coyote Trail
1. The Setting
The view across the canyon from the north facing slope to the south facing slope. Photo by Graham
The north-facing slopes and canyon bottoms are cool, shady and moist; while the south-facing slopes are hot, sunny and dry. Coast live oak, Quercus agrifolia, is the dominant plant with scattered shrubs of laurel sumac, toyon and elderberry.
Calling It Names ...
This fits pretty well, but what about the oaks? Where do they come in?
He goes on to say Southern Oak Woodland is dominated by one of the large oak species. In our case, it is coast live oak. This woodland occurs on moist sites with deep soil on canyon bottoms and north-facing slopes. Live Oak Woodlands exist as islands within Coastal Sage Scrub.
The leaves of coast live oak are highly variable. These leaves in the shade are flatter and larger than those in the sun. Photo by Graham.
"The leaves are dark green, oval, often convex in shape; the leaf margin is spiny-toothed, with sharp thistly fibers that extend from the lateral leaf veins. (The name Quercus agrifolia literally means "sharp-leaved oak", not "field-leaved oak" as is sometimes thought.) The outer layers of leaves are designed for maximum solar absorption, containing two to three layers of photosynthetic cells. These outer leaves are deemed to be small in size to more efficiently re-radiate the heat gained from solar capture. Shaded leaves are generally broader and thinner, having only a single layer of photosynthetic cells. The convex leaf shape may be useful for interior leaves which depend on capturing reflected light scattered in random directions from the outer canopy." from Coast Live Oak in Wikipedia
What we saw: