''Quercus parvula'', the Santa Cruz Island oak, is an evergreen

red oak The genus ''Quercus'' contains about 500 species, some of which are listed here. The genus, as is the case with many large genera, is divided into subgenera and sections. Traditionally, the genus ''Quercus'' was divided into the two subgenera '' ...

(Series ''Agrifoliae'', Section '' Lobatae'') found on north-facing

Santa Cruz Island Santa Cruz Island ( Spanish: ''Isla Santa Cruz'', Chumash: ''Limuw'') is located off the southwestern coast of Ventura, California, United States. It is the largest island in California and largest of the eight islands in the Channel Islands ...

slopes and in the

California Coast Ranges The Coast Ranges of California span from Del Norte or Humboldt County, California, south to Santa Barbara County. The other three coastal California mountain ranges are the Transverse Ranges, Peninsular Ranges and the Klamath Mountains. Ph ...

from

Santa Barbara County Santa Barbara County, California, officially the County of Santa Barbara, is located in Southern California. As of the 2020 census, the population was 448,229. The county seat is Santa Barbara, and the largest city is Santa Maria. Santa Barba ...

north to

Mendocino County Mendocino County (; ''Mendocino'', Spanish for "of Mendoza) is a county located on the North Coast of the U.S. state of California. As of the 2020 census, the population was 91,601. The county seat is Ukiah. Mendocino County consists wholly ...

. It was taxonomically combined with '' Quercus wislizeni'' until resurrected as a separate species by Kevin Nixon in 1980.K. Nixon, "A Systematic Study of ''Quercus parvula'' Greene on Santa Cruz Island and Mainland California," Master's Thesis, 1980. The

type locality Type locality may refer to: * Type locality (biology) * Type locality (geology) See also * Local (disambiguation) * Locality (disambiguation) {{disambiguation ...

of ''Q. parvula'' var. ''shrevei'' (originally described by C.H. Muller as ''Q. shrevei'') is Palo Colorado Canyon in Monterey County. Three varieties of ''Q. parvula'' are currently recognized:Jepson Flora Project (eds.) 2015 Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html July 17, 2015 ''Q. parvula'' differs morphologically from its close relative ''Q. wislizeni'' in the following ways: * Leaf blades are larger, > (2)4 cm long rather than < 4(6) cm * Leaf blades are thinner, generally < 0.26 mm near the apex rather than usually > 0.26 mm * Current year twigs are 5-sided rather than ± roundish in cross section * Leaf petioles and current year twigs are

glabrous Glabrousness (from the Latin '' glaber'' meaning "bald", "hairless", "shaved", "smooth") is the technical term for a lack of hair, down, setae, trichomes or other such covering. A glabrous surface may be a natural characteristic of all or part o ...

to sparsely hairy rather than moderately to very hairy * Nut tips are blunt rather than more sharply pointed * Abaxial golden glandular uniseriate leaf blade

trichomes Trichomes (); ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a pla ...

are missing or sparse rather than moderate to dense * Abaxial multiradiate leaf blade trichomes are missing or sparse on the midvein rather than occasional to common * Secondary leaf blade veins are raised abaxially rather than ± not raised ''Q. parvula'' and ''Q. wislizeni'' never produce newly emerging leaves with a velvety coating of red bulbous trichomes on the abaxial (upper) surface. This separates them from ''Q. kelloggii'' and both varieties of ''Q. agrifolia'' which produce such leaves.

Ecology

Mainland ''Q. parvula'' is commonly found with or near ''Sequoia sempervirens'' (coast redwood), and often near ''Q. agrifolia'' var. ''agrifolia'' (coast live oak) and ''Notholithocarpus densiflorus'' (tanoak). ''Q. parvula'' differs ecologically from ''Q. wislizeni'' in the following ways: * Island or coastal habitat rather than Sierra foothills * Associates with ''Sequoia sempervirens'' rather than ''Pinus sabiniana''

Hybridization

''Quercus parvula'' is theoretically capable of hybridizing with all of the other California red oaks except the higher elevation southern California ''Quercus agrifolia'' var. ''oxyadenia'' (sharpacorn oak)J.G. Cooper, Smithsonian Rep. 1858: 261 (1859) from which it is separated by the

Transverse Ranges The Transverse Ranges are a group of mountain ranges of southern California, in the Pacific Coast Ranges physiographic region in North America. The Transverse Ranges begin at the southern end of the California Coast Ranges and lie within San ...

. However ''Q. parvula'''s generally later flowering time (April–May versus February–April for ''Q. kelloggii'', ''Q. wislizeni'' and ''Q. agrifolia'') may limit genetic exchange with other '' Lobatae''.

References

{{Taxonbar, from=Q15339462 parvula