[calscape.org] Range, Habitat, Description, Hybridity: Quercus parvula var. shrevei, or Shreve Oak, is an evergreen red oak found in the California Coast Ranges from Santa Barbara County north to Mendocino County. It was taxonomically combined with Quercus wislizeni until resurrected as a separate species by Kevin Nixon in 1980. Recent work suggests Q. parvula var. parvula to be Q. parvula var. shrevei x Q. wislizeni. It generally occurs in foothills where it is common in the low elevations. It is a large shrub or tree growing to 22 meters (73 feet) tall, although it seldom exceeds 10 meters (33 feet). The dark-green leaves -appearing grayish from a distance. Leaves are usually small, 2 to 5 cm long, thick, and often spiny-toothed at higher elevations. All California red oaks show evidence of introgression and/or hybridization with one another. (link added by Mary Ann Machi)