Fine Art

Interior live oak twig with acorn

Classification System: APG IV

Superregnum: Eukaryota
Regnum: Plantae
Cladus: Angiosperms
Cladus: Eudicots
Cladus: Core eudicots
Cladus: Rosids
Cladus: Eurosids I
Ordo: Fagales

Familia: Fagaceae
Genus: Quercus
Species: Quercus wislizeni
Varieties: Q. w. var. frutescens – Q. w. var. wislizeni

Quercus wislizeni DC., 1864

Quercus × morehus

Native distribution areas:

Continental: Northern America
Regional: Southwestern USA
Regional: Mexico
Mexico Northwest

References: Brummitt, R.K. 2001. TDWG – World Geographical Scheme for Recording Plant Distributions, 2nd Edition
Primary references

De Candolle, A.P. in Candolle, 1864. Prodr. 16(2): 67

Additional references

Govaerts, R.H.A. & Frodin, D. 1998. World Checklist and Bibliography of Fagales (Betulaceae, Corylaceae, Fagaceae and Ticodendraceae). VIII + 408 p. The Board of Trustees of the Royal Botanic Gardens, Kew. ISBN 1-900347-46-6. Reference page.


Govaerts, R. et al. 2021. Quercus wislizeni in World Checklist of Selected Plant Families. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the internet. Accessed: 2021 Jul 04. Reference page.
Govaerts, R. et al. 2021. Quercus wislizeni in Kew Science Plants of the World online. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the internet. Accessed: 2021 Jul 04. Reference page.
International Plant Names Index. 2021. Quercus wislizeni. Published online. Accessed: Jul 04 2021. 2021. Quercus wislizeni. Missouri Botanical Garden. Published on the internet. Accessed: 2021 Jul 04.
Hassler, M. 2021. Quercus wislizeni. World Plants: Synonymic Checklists of the Vascular Plants of the World In: Roskovh, Y., Abucay, L., Orrell, T., Nicolson, D., Bailly, N., Kirk, P., Bourgoin, T., DeWalt, R.E., Decock, W., De Wever, A., Nieukerken, E. van, Zarucchi, J. & Penev, L., eds. 2021. Species 2000 & ITIS Catalogue of Life. Published on the internet. Accessed: 2021 Jul 04. Reference page.
Hassler, M. 2021. World Plants. Synonymic Checklist and Distribution of the World Flora. . Quercus wislizeni. Accessed: 04 Jul 2021.
USDA, ARS, Germplasm Resources Information Network. Quercus wislizeni in the Germplasm Resources Information Network (GRIN), U.S. Department of Agriculture Agricultural Research Service. Accessed: 07-Oct-06.

Vernacular names
English: Interior Live Oak

Quercus wislizeni, known by the common name interior live oak,[4] is an evergreen oak, highly variable and often shrubby, found in many areas of California[5] in the United States continuing south into northern Baja California in Mexico. It generally occurs in foothills, being most abundant in the lower elevations of the Sierra Nevada, but also widespread in the Pacific Coast Ranges ─ where since 1980 it has been known as a separate species Quercus parvula[6][7] ─ and the San Gabriel Mountains. It was named for its collector, Friedrich Adolph Wislizenus (1810–1889).[4]


It is a large shrub or tree[8] growing to 22 meters (72 feet) tall, although where it is common in the low elevation Sierra foothills it seldom exceeds 10 meters (33 feet). The dark-green leaves ─ appearing grayish from a distance ─ are usually small, 2–5 cm (1–2 in) long, thick, and often spiny-toothed at higher elevations, particularly on young trees. The male flowers are on catkins, the female flowers in leaf axils. The acorns are 1–2 cm (0.5–1 in) long, and mature the second season (about 18 months) after flowering.[8]

Although originally published by Alphonse Pyramus de Candolle as "wislizeni",[2] some sources, e.g., Jensen in Flora of North America,[8] mistakenly spelled the specific epithet "wislizenii." Correct spelling is with one "i," per ICN article 60C.2.[9] Wislizenus' specimen was thought by de Candolle to have been collected in Chihuahua, Mexico. However, German-born American botanist Georg Engelmann later corrected the location to the American fork of the Sacramento River near Auburn, California.

California physician and botanist (and one of the founding fathers of the California Academy of Sciences) Albert Kellogg described an oak in an 1855 publication as Quercus arcoglandis (spur acorn oak),[10] apparently the same species as Q. wislizeni. This clearly predates French-Swiss botanist de Candolle's 1864 name, and if confirmed to be this same taxon would have priority. More investigation is needed to resolve this taxonomic conflict.

Currently there are two recognized varieties of interior live oak:[11]

Q. wislizeni A. DC. var. wislizeni (1864)
Q. wislizeni A. DC. var. frutescens Engelm (1878).[12] This is an invalid taxon. Engelmann's Q. wislizeni var. frutescens description is virtually identical to de Candolle's Q. wislizeni, while Engelmann's Q. wislizeni description most closely matches Kellogg's Q. morehus.[13]


The interior live oak is a red oak (section Lobatae) in the California Floristic Province (series Agrifoliae). Q. wislizeni hybridizes with California black oak (Q. kelloggii) (= Quercus × morehus, Abram's oak). All California red oaks show evidence of introgression and/or hybridization with one another.

A common alliant tree is gray pine (Pinus sabiniana).[13]

Deer browse the tree's foliage. Humans use the wood as a fuel source.[14]

Jerome, D. (2017). "Quercus wislizeni". IUCN Red List of Threatened Species. 2017: e.T89254808A89254811. doi:10.2305/IUCN.UK.2017-2.RLTS.T89254808A89254811.en. Retrieved 11 November 2021.
de Candolle, Alphonse Pyramus (1864). "Q. wislizeni". Prodromus Systematis Naturalis Regni Vegetabilis (in Latin). Vol. 16. p. 67.
"Quercus wislizeni A.DC". IPNI. Retrieved August 29, 2010. "Description of Q. wislizeni was published in Prodromus Systematis Naturalis Regni Vegetabilis ... (DC.) 16(2.1): 67 (1864)."[2]
"Quercus wislizeni A.DC.". Tropicos. Missouri Botanical Garden. Retrieved August 9, 2010.
"Quercus wislizeni". Calflora. Berkeley, California: The Calflora Database.
Nixon, Kevin (1980). A Systematic Study of Quercus parvula Greene on Santa Cruz Island and Mainland California (Master's Thesis).
Jepson eFlora: Quercus parvula.
Flora of North America.
J. McMeill et al. (eds). 2012. International Code of Nomenclature for algae, fungi, and plants. Regnum Vegetabile 154. Koeltz Scientific Books. ISBN 978-3-87429-425-6
Kellogg, Proc. Calif. Acad. 1(1):25 (1855)
Jepson eFlora: Quercus wislizeni.
Engelm., Trans. Acad. Sci. St. Louis 3:396 (1878).
Duncan A. Hauser; Al Keuter; John D. McVay; Andrew L. Hipp; Paul S. Manos (October 2017). "The evolution and diversification of the red oaks of the California Floristic Province (Quercus section Lobatae, series Agrifoliae)". Am. J. Bot. 104 (10): 1581–1595. doi:10.3732/ajb.1700291. PMID 29885216.

Whitney, Stephen (1985). Western Forests. The Audubon Society Nature Guides. New York: Knopf. p. 382. ISBN 0-394-73127-1.

Nixon, Kevin C. (1997). "Quercus wislizeni". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 3. New York and Oxford – via, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
Rosatti, Thomas J.; Tucker, John M. (2014). "Quercus parvula". In Jepson Flora Project (ed.). Jepson eFlora. The Jepson Herbarium, University of California, Berkeley.
Rosatti, Thomas J.; Tucker, John M. (2014). "Quercus wislizeni". In Jepson Flora Project (ed.). Jepson eFlora. The Jepson Herbarium, University of California, Berkeley.

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