A N F Keys
1 Plants winter-deciduous, trees with tough, pliable leaves having rounded lobes, 45−110(−140) × 25−90(−110) mm; acorn (shell) 37−61 × 13−22 mm, basal scar (7.5−)9−11 mm diameter, cup with densely short-hairy bumpy scales and glabrous inside surface .. Quercus lobata [pics]
1' Plants ± evergreen, trees or shrubs maintaining sclerophyllous leaves with or without spinose margins, 15−75 × 8−54 mm; acorns never > 45 mm long and basal scar always < 6.5 mm diameter
2 Blades elliptic or roundish to ovate, coarsely toothed and spinose on margins at tip (entire) and on old leaves upper surface dark green, lower surface glabrescent with hairs mostly persistent along midrib; acorn shell internally densely woolly, scales ± flat and thin often with short-ciliate margins
3 Large trees with dense canopy and thick trunk, 6−20+ m tall; blades usually strongly cupped; acorns maturing and abscising in same year, basal scar typically 5−6 mm diameter .. Quercus agrifolia var. agrifolia [pics]
3' Shrubs with open canopy, in range < 4 m tall; blades flat; acorns persistent until year 2, basal scar 4−5 mm diameter .. Quercus wislizeni [pics]
2' Blades oblong to elliptic or obovate, often toothed to shallowly lobed and teeth sometimes spine-tipped; acorn scales warty (tuberculate) to ± fleshy
4 Blades mildly spinose on margins or not conspicuously spinescent, when young lacking dense "glandular" hairs and having only stellate hairs with widely spreading arms; acorn shell internally glabrous
5 Shrubs to small tree with burl (if fire-affected); stipules typically 5.5−7 mm long, tomentose at least at base; blades minutely stellate-pubescent; filaments 1−2.5 mm long; acorns ovoid to ellipsoid and acute to obtuse at tip .. Quercus berberidifolia [pics]
5' Tree with several trunks; stipules < 5 mm long, mostly short-stigose; blades initially with silvery white stellate hairs, often aging glaucous; filaments < 1 mm long; acorns not observed (2-year), ± cylindric and acuminate at tip .. Quercus douglasii [pics]
4' Blades conspicuously and sharply spinescent, when young with dense, ephemeral, "glandular" hairs; acorns mature and abscising after second summer (2-year), acorn shell internally densely woolly .. Quercus palmeri [pics]
NB. In range not all oaks produce acorns or have them present for identification, and stipules and staminate inflorescences may be useful but are short-lived, so that leaf features must be used in this key, even though blades are highly variable and overlap for several species. Quercus berberidifolia is the current name of the common scrub oak in range, formerly treated as Q. dumosa Nutt., and all attempts to find in range reliable Q. dumosa were unsuccessful. Quercus durata Jepson var. gabrielensis Nixon & C. H. Muller is recorded in databases as being in the Hollywood Hills (SMM), but critical study of existing herbarium materials and new field work has not convinced us yet that this is correct.
The text of the above keys used with permission from
A Naturalist's Flora of the Santa Monica Mountains and Simi Hills, California
© Copyright
Barry A. Prigge and Arthur C. Gibson
2013