Coast live oak | |
---|---|
Coast live oak foliage with new spring growth | |
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 | |
Natural range | |
Synonyms [2] | |
List
|
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). [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.
Coast live oak typically has a much-branched trunk and reaches a mature height of 10–25 metres (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 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. [8] The oldest specimens might exceed 6 m (20 ft) in trunk circumference and 30 m (100 ft) in height. [11] [12]
The leaves are dark green, oval, often convex in shape, 2–7 centimetres (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. [8]
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. [8] 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". [13]
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). [8]
There are two varieties of Quercus agrifolia:
Image | Scientific name | Description | Distribution |
---|---|---|---|
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 known (Q. x ganderi). | Southwesternmost California (San Diego area), Baja California. | |
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. Coast live oak also hybridizes with Shreve oak (Q. parvula var. shrevei). All these oak species show evidence of introgression with one another.
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.' [14] [15] [16]
Normally the tree is found on well-drained soils of coastal hills and plains, often near year-round or perennial streams. It may be found in several natural communities including coast live oak woodland, Engelmann oak woodland, valley oak woodland and both northern and southern mixed evergreen forests. While normally found within 100 kilometers (62 miles) of the Pacific Ocean at elevations less than 700 m (2,300 ft), in southern California it occasionally occurs at up to 1,500 m (4,900 ft) in elevation.
It is the only California native oak that thrives in the coastal environment, although it is rare on the immediate shore; it enjoys the mild winter and summer climate afforded by ocean proximity, and it is somewhat tolerant of aerosol-borne sea salt. The coastal fog supplies relief from the rainless California summer heat.
It is the dominant overstory plant of the coast live oak woodland habitat, often joined by California bay laurel and California buckeye north of Big Sur. Associated understory plants include toyon, various manzanitas and western poison-oak.
The California oak moth ( Phryganidia californica ) caterpillar subsists entirely on living and fallen leaves of the Coast Live Oak. In 8–10 year cycles, the caterpillar 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. [17] 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. [18]
The pollen of the coast live oak is a severe allergen. Pollination occurs in spring. [19]
This section possibly contains original research .(May 2024) |
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. [20] A particular usefulness of the tree lies in its ability to yield acorns in winter season as well. 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.
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. [21]
Santa Maria–style barbecue is grilled over coals of coast live oak.
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. [22]
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.
Quercus kelloggii, the California black oak or Kellogg oak, is an oak in the red oak section native to western North America. Although genetically separated from them for more than 20 million years, its leaves are remarkably similar in appearance to several other members of the red oak section including the red oak and the black oak found in eastern and central North America.
Quercus palustris, also called pin oak, swamp oak, or Spanish oak, is a tree in the red oak section of the genus Quercus. Pin oak is one of the most commonly used landscaping oaks in its native range due to its ease of transplant, relatively fast growth, and pollution tolerance.
Quercus garryana is an oak tree species of the Pacific Northwest, with a range stretching from southern California to southwestern British Columbia. It is commonly known as the Garry Oak, Oregon white oak or Oregon oak. It grows from sea level to an altitude of 690 feet in the northern part of its range, and from 980 to 5,900 ft in the south of the range in California. The eponymous Nicholas Garry was deputy governor of the Hudson's Bay Company.
Quercus cerris, the Turkey oak or Austrian oak, is an oak native to south-eastern Europe and Asia Minor. It is the type species of Quercus sect. Cerris, a section of the genus characterised by shoot buds surrounded by soft bristles, bristle-tipped leaf lobes, and acorns that usually mature in 18 months.
Quercus suber, commonly called the cork oak, is a medium-sized, evergreen oak tree in the section Quercus sect. Cerris. It is the primary source of cork for wine bottle stoppers and other uses, such as cork flooring and as the cores of cricket balls. It is native to southwest Europe and northwest Africa. In the Mediterranean basin the tree is an ancient species with fossil remnants dating back to the Tertiary period. It can survive for as long as two centuries. Typically, once it reaches 25 years old, its thick bark can be harvested for cork every 9 to 12 years without causing harm to the tree.
Quercus virginiana, also known as the southern live oak, is an evergreen oak tree endemic to the Southeastern United States. Though many other species are loosely called live oak, the southern live oak is particularly iconic of the Old South. Many very large and old specimens of live oak can be found today in the Deep South region of the United States.
Quercus macrocarpa, the bur oak or burr oak, is a species of oak tree native to eastern North America. It is in the white oak section, Quercus sect. Quercus, and is also called mossycup oak, mossycup white oak, blue oak, or scrub oak. The acorns are the largest of any North American oak, and are important food for wildlife.
Quercus douglasii, known as blue oak, is a species of oak endemic to California, common in the Coast Ranges and the foothills of the Sierra Nevada. It is California's most drought-tolerant deciduous oak, and is a dominant species in the blue oak woodland ecosystem. It is occasionally known as mountain oak and iron oak.
Quercus gambelii, with the common name Gambel oak, is a deciduous small tree or large shrub that is widespread in the foothills and lower mountains of western North America. It is also regionally called scrub oak, oak brush, and white oak.
Quercus phellos, the willow oak, is a North American species of a deciduous tree in the red oak group of oaks. It is native to the south-central and eastern United States.
Aesculus californica, commonly known as the California buckeye or California horse-chestnut, is a species of buckeye native to California and southwestern Oregon.
Quercus lobata, commonly called the valley oak or roble, is the largest of the California oaks. It is endemic to the state, growing in interior valleys and foothills from Siskiyou to San Diego counties. Deciduous, it requires year-round groundwater, and may live up to 600 years. Its thick, ridged bark and deeply lobed leaves are characteristic, and assist in identification.
Quercus lyrata, the overcup oak, is an oak in the white oak group. The common name, overcup oak, refers to its acorns that are mostly enclosed within the acorn cup. It is native to lowland wetlands in the eastern and south-central United States, in all the coastal states from New Jersey to Texas, inland as far as Oklahoma, Missouri, and Illinois. There are historical reports of it growing in Iowa, but the species appears to have been extirpated there. It is a slow-growing tree that often takes 25 to 30 years to mature. It has an estimated lifespan of 400 years.
Quercus nigra, the water oak, is an oak in the red oak group, native to the eastern and south-central United States, found in all the coastal states from New Jersey to Texas, and inland as far as Oklahoma, Kentucky, and southern Missouri. It occurs in lowlands and up to 450 meters in elevation.
Quercus chrysolepis, commonly termed canyon live oak, canyon oak, golden cup oak or maul oak, is a North American species of evergreen oak that is found in Mexico and in the western United States, notably in the California Coast Ranges. This tree is often found near creeks and drainage swales growing in moist cool microhabitats. Its leaves are a glossy dark green on the upper surface with prominent spines; a further identification arises from the leaves of canyon live oak being geometrically flat.
Quercus durata, commonly known as leather oak, is a species of oak endemic to California, common in the Coast Ranges and the foothills of the Sierra Nevada. The common name "leather oak" is derived from the leathery texture on the lop of its leaves. Taxonomically it is placed in the white oak group.
Quercus turbinella is a North American species of oak known by the common names shruboak, turbinella oak, shrub live oak, and gray oak. It is native to Arizona, California, New Mexico, Utah, Colorado, and Nevada in the western United States. It also occurs in northern Mexico.
Quercus pacifica is a species of oak known by the common names island scrub oak, Channel Island scrub oak, and Pacific oak.
Quercus oblongifolia, commonly known as the Mexican blue oak, Arizona blue oak, Blue live oak or Sonoran blue oak, is an evergreen small tree or large shrub in the white oak group.
Notholithocarpus densiflorus, commonly known as the tanoak or tanbark-oak, is a broadleaf tree in the family Fagaceae, and the type species of the genus Notholithocarpus. It is native to the far western United States, particularly Oregon and California. It ranges from 15–40 meters in height, with a trunk diameter of 60–190 centimeters.
{{cite book}}
: CS1 maint: location missing publisher (link)