Quercus agrifolia

Evergreen oak tree native to California

Coast live oak

Coast live oak foliage

Conservation status

Secure  (NatureServe)[1]

Scientific classification
Kingdom:  | Plantae
Clade:  | Tracheophytes
Clade:  | Angiosperms
Clade:  | Eudicots
Clade:  | Rosids
Order:  | Fagales
Family:  | Fagaceae
Genus:  | Quercus
Subgenus:  | Quercus subg. Quercus
Section:  | Quercus sect. Lobatae
Species:  |

Q. agrifolia

Binomial name
Quercus agrifolia

Née

Natural range
Synonyms[2]

List

* Quercus acroglandis Kellogg
* Quercus acutiglandis Sarg.
* Quercus agrifolia var. frutescens Engelm.
* Quercus agrifolia var. oxyadenia (Torr.) J.T.Howell
* Quercus oxyadenia Torr.
* Quercus pricei Sudw.

Quercus agrifolia, the California live oak,[3] or coast live oak, is an evergreen[4] live oak native to the California Floristic Province. Live oaks are so-called because they keep living leaves on the tree all year, adding young leaves and shedding dead leaves simultaneously rather than dropping dead leaves en masse in the autumn like a true deciduous tree.[5] Coast live oaks may be shrubby, depending on age and growing location, but is generally a medium-sized tree.[6] It grows west of the Sierra Nevada mountain range from Mendocino County, California, south to northern Baja California in Mexico.[7] It is classified in the red oak section of oaks (Quercus sect. Lobatae), subsection Agrifoliae.[8]

This species is commonly sympatric with canyon live oak (Q. chrysolepis), and the two may be hard to distinguish because their spinose leaves are superficially similar.

## Description

[edit]

Coast live oak typically has a much-branched trunk and reaches a mature height of 10–25 meters (33–82 feet). Some specimens may attain an age exceeding 1,000 years. Examples of this include the Grand Oak of Cherry Valley, California,[9] the Encino Oak Tree, which died in the 1990s (part of the stump has been preserved)[10] and the Pechanga Great Oak.[11] The tree is extremely drought-tolerant.[3]

The trunk, particularly for older individuals, may be highly contorted, massive and gnarled. The crown is broadly rounded and dense, especially when aged 20 to 70 years; in later life the trunk and branches are more well defined and the leaf density lower.[12] The oldest specimens might exceed 6 m (20 ft) in trunk circumference and 30 m (100 ft) in height.[11][13]

The leaves are dark green, oval, often convex in shape, 2–7 centimeters (3⁄4–2+3⁄4 inches) long and 1–4 cm (1⁄2–1+1⁄2 in) broad; the leaf margin is spiny-toothed (spinose), with sharp thistly fibers that extend from the lateral leaf veins. The outer layers of leaves are designed for maximum solar absorption, containing two to three layers of photosynthetic cells.[12]

These outer leaves are deemed to be small in size to more efficiently re-radiate the heat gained from solar capture. Shaded leaves are generally broader and thinner, having only a single layer of photosynthetic cells. The convex leaf shape may be useful for interior leaves which depend on capturing reflected light scattered in random directions from the outer canopy.[12] The leaf shape may be also useful as condensation surfaces for "dew and mist, which would allow the tree to survive years with limited rainfall".[14]

The flowers are produced in early-to-mid spring; the male flowers are pendulous catkins 5–10 cm (2–4 in) long, the female flowers inconspicuous, less than 0.5 cm (1⁄4 in) long, with 1–3 clustered together. The fruit is a slender reddish brown acorn 2–3.5 cm (3⁄4–1+1⁄2 in) long and 1–1.5 cm (3⁄8–5⁄8 in) broad, with the basal quarter enclosed in a cupule; unusually for a red oak, the acorns mature about 7–8 months after pollination (most red oak acorns take 18 months to mature).[12]

Q. agrifolia acorns and leaves

### Recognized varieties

[edit]

There are two varieties of Quercus agrifolia:

Image | Scientific name | Description | Distribution

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|
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| Quercus agrifolia var. agrifolia | Leaves that are glabrous to slightly hairy on the abaxial side, especially near the leaf vein axils. Hybrids with Q. kelloggii, Q. parvula var. shevei, and Q. wislizeni are known. | Throughout the range of the species.
| Quercus agrifolia var. oxyadenia | Leaves that are tomentose abaxially, with densely interwoven hairs. It prefers granitic soils; hybrids with Q. kelloggii are known (Q. x ganderi). | Southwesternmost California (San Diego area), Baja California.

### Hybridity

[edit]

Several hybrids between coast live oak and other red oak species have been documented. Hybrids with interior live oak (Q. wislizenii) are known in many areas in northern California.[15] Coast live oak also hybridizes with Shreve oak (Q. parvula var. shrevei). All these oak species show evidence of introgression with one another.[16]

## Etymology

[edit]

In naming the species, Née compared it to a species illustrated in Leonard Plukenet's Phytographia under the descriptive name "Ilex folio agrifolii americana, forte agria, vel aquifolia glandifera" which Plukenet had compared, in his Almagestum botanicum, to Luigi Anguillara's Agrifolia glandifera, the noun 'Agrifolia' being a Medieval Latin form of 'Aquifolium' meaning a holly or holly-leaved oak, and related to the Modern Italian 'Agrifoglio', meaning 'holly'.[17][18][19]

## Distribution and habitat

[edit]

Coast live oak, San Luis Obispo County, California

The Coast Live Oak is typically found within 100 km (62 m) of the Pacific Ocean, living on coastal hills and plains and preferring soil with good drainage as well as proximity to perennial streams. It often lives in communities with other native oaks and sometimes in mixed evergreen forests. It generally prefers elevations less than 700 m (2,300 ft), but can be found as high as 1,500 m (4,900 ft) in some places. The Coast Live Oak typically enjoys the climate of near-coastal environments; it has a higher-than-average tolerance for airborne salinity, allowing coastal fog to make up for the lack of rain during much of the year.[20]

## Ecology

[edit]

Some species associated with coast live oak: Pacific poison oak, California camouflage lichen, viscid bolete, oak titmouse, California sister, live-oak apple, acorn woodpecker, lace lichen, live oak witch's broom, Bewick's wren

Coast Live Oaks are the dominant tree in the Coast Live Oak Woodland habitat. This habitat often contains other shrubs and vines, including toyon, California coffeeberry, California man-root, bitter gooseberry, California wild rose, Hummingbird sage, blue elderberry, and poison-oak.[21]

The caterpillars of the California oak moth (Phryganidia californica) subsist entirely on living and fallen leaves of the Coast Live Oak. In 8–10 year cycles, the caterpillars will appear in sufficient abundance to denude healthy trees. The trees recover, and botanists speculate that the species provide mutual benefit, possibly in the form of fertilizer for the oak.[22] The coast live oak is also the only known foodplant of Chionodes vanduzeei caterpillars.

Live oak trees, among other western oaks, are also known to support acorn woodpeckers, which store their acorns in tree trunks and remove them when they want to eat. [23]

## Allergenicity

[edit]

The pollen of the coast live oak is a severe allergen. Pollination occurs in spring.[24]

## Uses

[edit]

### Historical

[edit]

This section possibly contains original research. Please improve it by verifying the claims made and adding inline citations. Statements consisting only of original research should be removed. (May 2024) (Learn how and when to remove this message)

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Coast live oak at Rancho Los Encinos in the San Fernando Valley

At least twelve distinct cultures of Native Americans are known to have consumed the acorns as a dietary staple.[citation needed] The seeds were ground into meal, which after being washed was boiled into mush or baked in ashes to make bread.[25] A particular usefulness of the tree lies in its ability to yield acorns in winter season as well[4]. In the 18th century, Spaniards in the San Fernando Valley used the wood for charcoal to fire kilns in making adobe. Later this form of charcoal would be utilized in the baking, gunpowder and electric power industries.

In the 18th and 19th centuries shipbuilders sought out the odd angular branches to make special joints. Pioneers moving west would harvest small amounts for making farm implements and wagon wheels, but the greatest impact was the wholesale clearing of oak woodlands to erect sprawling cities such as San Diego and San Francisco. The irregular shape often let the tree escape widespread harvest for building timbers, and also led the early settlers to endow the coast live oak with mystical qualities. Its stateliness has made it a subject of historical landscape painters throughout California modern history since the mid-19th century.

### Modern

[edit]

This section relies largely or entirely on a single source. Relevant discussion may be found on the talk page. Please help improve this article by introducing citations to additional sources.
Find sources: "Quercus agrifolia" – news · newspapers · books · scholar · JSTOR (August 2024)

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Coast live oak has also become a common addition to western US landscaping. It is however sensitive to changes in grading and drainage; in particular, it is important to respect the root crown level and avoid adding soil near the trunk when construction or landscaping occurs.

Also, if incorporating it into a landscaping scheme with artificial irrigation, it is important to avoid regular watering within the oak's drip line (canopy), since wet soil in the summer increases infection rates by soil-borne Phytophthora diseases like sudden oak death.[26]

Santa Maria–style barbecue is grilled over coals of coast live oak.

## Culture

[edit]

The coast live oak, especially in its Spanish forms encino or encina, encinitas "little oaks", and encinal "oak grove", gave its name to seven land grants across California and to many communities and geographic features. These include Rancho Los Encinos, the Los Angeles community of Encino, Encinitas near San Diego, and Encinal del Temescal, now the city of Oakland.[27]

Paso Robles (fully 'El Paso de Robles' or 'Pass of the Oaks') also refers to the ubiquitous live oaks in the region as a geographical place name.

## References

[edit]

1. ^ Beckman, E. (2016). "Quercus agrifolia". IUCN Red List of Threatened Species. 2016: e.T194049A2295175. doi:10.2305/IUCN.UK.2016-1.RLTS.T194049A2295175.en. Retrieved 12 November 2021.
2. ^ "Quercus agrifolia Née". World Checklist of Selected Plant Families. Royal Botanic Gardens, Kew - via The Plant List. Note that this website has been superseded by World Flora Online
3. ^ NRCS. "Quercus agrifolia". PLANTS Database. United States Department of Agriculture (USDA). Retrieved 30 July 2015.
4. ^ "Plant Guide: Coast live oak (Quercus agrifolia)" (PDF). plants.usda.gov. p. 1 (col 2).
5. ^ Educate, Sandra (2021-12-07). "Learning about Live Oaks | Lowcountry Weekly". Retrieved 2024-05-18.
6. ^ Sibley, David (2009). The Sibley guide to trees (First ed.). New York. p. 202\. ISBN 978-0375415197. OCLC 277201819.`{{cite book}}`: CS1 maint: location missing publisher (link)
7. ^ "Quercus agrifolia". Calflora. Berkeley, California: The Calflora Database.
8. ^ Manos, Paul S.; Hipp, Andrew L. (2021-06-15). "An Updated Infrageneric Classification of the North American Oaks (Quercus Subgenus Quercus): Review of the Contribution of Phylogenomic Data to Biogeography and Species Diversity". Forests. 12 (6): 786. doi:10.3390/f12060786. ISSN 1999-4907.
9. ^ "Coast Live Oak 'The Grand Oak' at Highland Springs Resort, Cherry Valley, California, United States". www.monumentaltrees.com.
10. ^ "Grand Old Tree: Lang Oak Praised on Arbor Day", Daily News, Los Angeles, March 8, 1997
11. ^ a b "Pechanga Band of Indians - The Great Oak". www.pechanga-nsn.gov.
12. ^ a b c d Nixon, Kevin C. (1997). "Quercus agrifolia". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 3\. New York and Oxford: Oxford University Press - via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
13. ^ "The Great Encino Oak Tree".
14. ^ "Coastal live oak - Quercus agrifolia". Santa Monica Mountains Trails Council. Retrieved 2023-11-10.
15. ^ Brophy, William B.; Parnell, Dennis R. (1974). "Hybridization Between Quercus Agrifolia and Q. Wislizenii (fagaceae)". Madroño. 22 (6): 290–302\. ISSN 0024-9637. JSTOR 41423936.
16. ^ Richard S. Dodd, Nasser Kashani, and Zara Afzal-Rafii (2023). "Population Diversity and Evidence of Introgression Among the Black Oaks of California". US Forest Service.`{{cite journal}}`: CS1 maint: multiple names: authors list (link)
17. ^ Née, Luis. Descripción de varias especies nuevas de 'Encina' (Quercus de Linneo). Anales de historia natural. volume 3. 1801.[1]
18. ^ Plukenet, Leonard. Phytographia [...] Pars tertia, 1692 [2]
19. ^ Plukenet, Leonard. Almagestum botanicum, 1696
20. ^ "Coast Live Oak". Golden Gate National Parks Conservancy. 2018-09-04. Retrieved 2025-03-26.
21. ^ "Coast Live Oak Woodland | North Campus Open Space". www.ncos.ccber.ucsb.edu. Retrieved 2025-03-26.
22. ^ "Quercus (Oak) Notes – Trees of Stanford & Environs". trees.stanford.edu.
23. ^ Koenig, Walt. "The Enduring Mystery of Oak Tree "Mast" Years". Bay Nature.
24. ^ "Coastal Live Oak (Quercus agrifolia) Species Details and Allergy Info, Santa clara county, California".
25. ^ Whitney, Stephen (1985). Western Forests (The Audubon Society Nature Guides). New York: Knopf. p. 383. ISBN 0394731271.
26. ^ J. M. Davidson (7 July 2003). "Sudden Oak Death and Associated Diseases Caused by Phytophthora ramorum". Plant Management Network. Retrieved 12 January 2010.
27. ^ Gudde, Erwin, and William Bright, California Place Names, University of California Press, 4th edition, 1998, ISBN 0520213165, pp. 123–124

## Bibliography

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* Balls, Edward Kent (2020) [1962]. Early Uses of California Plants. Berkeley, California: University of California Press. ISBN 978-0520343061. OCLC 1224278823.
* C. Michael Hogan, California Arts and Sciences Institute calasinstitute.org (2023) Coast Live Oak. ed. Arthur Dawson. Encyclopedia of Earth. National Council for Science and Environment. Washington DC
* Mensing, Scott (2015). "The Paleohistory of California Oaks". Proceedings of the Seventh California Oak Symposium: Managing Oak Woodlands in a Dynamic World. 251. Berkeley, California: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 35–47\. Gen. Tech. Rep. PSW-GTR-251.
* Pavlik, Bruce M.; Muick, Pamela C.; Johnson, Sharon G.; Popper, Marjorie (1991). Oaks of California. Los Olivos, California: Cachuma Press. ISBN 0962850519.
* Sawyer, John O.; Keeler-Wolf, Todd (1995). A Manual of California Vegetation. California Native Plant Society. p. 241\. ISBN 978-0943460260.
* Steinberg, Peter D. (2002). "Quercus agrifolia". Fire Effects Information System Online. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

## External links

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Wikimedia Commons has media related to Quercus agrifolia.

* "Quercus agrifolia". Native Plant Database. Lady Bird Johnson Wildflower Center, University of Texas at Austin.
* Las Pilitas: California Oaks
* Virginia Tech Forestry Department: Coast Live Oak
* USDA Plants Database: Quercus agrifolia Née
* Interactive Distribution Map for Quercus agrifolia Archived 2012-06-07 at the Wayback Machine

Taxon identifiers

Quercus agrifolia|

* Wikidata: Q514052
* Wikispecies: Quercus agrifolia
* Calflora: 6983
* CoL: 4R47M
* Ecocrop: 9096
* EoL: 1151806
* EPPO: QUEAG
* FEIS: queagr
* FNA: 233501005
* GBIF: 2880791
* GRIN: 30636
* iNaturalist: 47850
* IPNI: 295759-1
* ITIS: 19289
* IUCN: 194049
* NatureServe: 2.143622
* NCBI: 97693
* NZOR: 77984fdf-a6a3-42e3-a592-0876223e1669
* Open Tree of Life: 403384
* PfaF: Quercus agrifolia
* Plant List: kew-171483
* PLANTS: QUAG
* POWO: urn:lsid:ipni.org:names:295759-1
* RHS: 64645
* Tropicos: 13100025
* WFO: wfo-0000289442

Authority control databases: National |

* United States
* Israel

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