Where to photograph in California – Yahoo Groups (Calphoto) has a report for Mt. Tam.
The Mountain is covered in wildflowers, from Ceanothus to Calypso Orchids. Driving up to Rock Springs, the side of Panoramic is covered in lupines and California poppies
Almost every curve has a waterfall.
The Serpentine Outcropping across from Rock Springs is covered in Goldfields, poppies, phacelia, pinks and a myriad of other wildflowers, Hills have a blue hue on them from all the lupines.
The trail to Cataract has Mission Bells, Calypso Orchids, Shooting stars (past peak) Milkmaids (like anyone cares) California Buttercups, Miners Lettuce (making for a nice snack) Western Hounds Tongue.
There is much Lichen and fungi as well as ferns unfurling in the cool breeze of the canyon. Look out for Turkey Vultures, Ravens, American Dippers, Acorn Woodpeckers and I heard an Owl calling just east of the top meadow near the trailhead.
Along West Ridgecrest, Annual and Perennial Lupines and California Poppies dominate.