California holm oak

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California holm oak
California Holm Oak foliage with fresh spring shoots

California Holm Oak foliage with fresh spring shoots

Systematics
Class : Bedecktsamer (Magnoliopsida)
Eurosiden I
Order : Beech-like (Fagales)
Family : Beech family (Fagaceae)
Genre : Oak trees ( Quercus )
Type : California holm oak
Scientific name
Quercus agrifolia
Née
Distribution area of ​​the California holm oak

The California holm oak ( Quercus agrifolia ; English California live oak, coast live oak ) is a species of the beech family ( Fabaceae ). It is highly variable, often shrub-like and evergreen . It is based in California . The species grows west of the Sierra Nevada from Mendocino County in the north and south to the Mexican state of Baja California . The IUCN classifies the species as “not threatened” (“least concern”).

The species occurs sympatric with Quercus chrysolepis . Both species are very similar to each other because of their thorny leaves.

description

California Holm Oak in Sonoma County

The Californian holm oak usually has a multi-branched stem and reaches a height of 10 ... 25 meters when fully grown. Individual specimens can reach an age of 250 years, with trunk diameters of 3 ... 4 meters as with those in the Filoli estate in San Mateo County .

The trunk can be very curved and twisted, especially in older specimens, and is massive and gnarled. The crown is broadly rounded and dense, especially at the age of 20… 70 years; at an older age, the trunk and branches are easier to separate and the leaf density is lower.

leaves

The leaves are dark green, oval, often convex , 2… 7 cm long and 1… 4 cm wide; the leaf margin is prickly (spinose) with sharp fibers that emanate from the lateral leaf veins. The outer leaves are designed to make maximum use of sunlight by forming two to three layers of photosynthetically active cells.

These outer leaves are also smaller in order to better reflect the heat resulting from the strong sunlight. Leaves in shady areas are generally larger and thinner, with only a single layer of photosynthetically active cells. For the inner leaves, the convex shape could also serve to better capture the sunlight that is reflected from any direction or that is scattered by the outer leaves.

Flowers and fruits

Acorns and leaves

The flowers are produced from early to mid-spring; the male flowers are pendulous catkins 5 ... 10 centimeters long, the female flowers are inconspicuous, less than half a centimeter long and arranged in groups of up to three. The fruit is a slender, reddish-brown acorn , 2… 3.5 cm long and 1… 1.5 cm wide, the basal quarter of which is in a fruit cup ; Unusually for a representative of the red oak, the acorns ripen 7 ... 8 months after fertilization (with most red oaks only after 18 months).

Systematics

Quercus agrifolia belongs to the Lobatae section .

Well-known varieties

There are two varieties of Quercus agrifolia :

  • Quercus agrifolia var. Agrifolia . Occurs in the entire distribution area. The leaves are glabrous to slightly hairy on the underside; the hair is found especially in the armpits of the leaf veins. There are hybrids with California black oak ( Quercus kelloggii ) Q. parvula var. Shevei and Q. wislizenii known.
  • Quercus agrifolia var. Oxyadenia . In the extreme southwest of California (San Diego area) and Baja California. The leaves are felty underneath, with thick, interwoven hairs. She prefers granite floors; Hybrids with California Black Oak are known.

Hybridization

Several hybrids between California holm oaks and other species of the red oak section have been documented. Hybrids with Q. wislizenii ( English interior live oak ) are known from many areas in northern California. Californian holm oaks also hybridize with Q. parvula var. Shrevei . All of these species show evident signs of introgression with one another .

Synonyms

The Plant List , a joint venture between the Royal Botanic Gardens (Kew) and the Missouri Botanical Garden , lists the following synonyms:

  • Quercus acroglandis Kellogg
  • Quercus acülle coffin.
  • Quercus agrifolia var. Agrifolia
  • Quercus agrifolia var. Frutescens Engelm.
  • Quercus agrifolia var. Oxyadenia (Torr.) JTHowell
  • Quercus oxyadenia Torr.
  • Quercus pricei Sudw.

etymology

When naming the species, Née compared the species with one depicted in Leonard Plukenets Phytographia , which it listed under the descriptive name "Ilex folio agrifolii americana, forte agria, vel aquifolia glandifera" in his Almagestum botanicum and compared with Luigi Anguillara's "Agrifolia glandifera" would have. The noun "Agrifolia" is a Middle Latin form of "Aquifolium", which means a holly or a holly-leaved oak. It is to be equated with the modern Italian "Agrifoglio" with the meaning " holly ".

Habitat and Ecology

California holm oak on US Route 101 on the Central California coast

The California holm oak is the only oak species native to California that currently thrives on the coast, although it is also rare on the beach; it benefits from the mild winters and summers due to its proximity to the ocean and is somewhat tolerant of the salt from the spray. The coastal fog dampens the negative effects of the rainless Californian summer heat.

Q. agrifolia is the dominant tree species in the oak forests; it is often accompanied north of Big Sur by California laurel and California horse chestnut . Associated plants of the undergrowth are Heteromeles arbutifolia , bearberries ( English manzanitas ) and Toxicodendron diversilobum .

Usually the tree grows in well-ventilated soils in the coastal hills and plains, often near temporary or permanent streams. It can be found in various plant communities such as the holm oak forests, Quercus engelmannii forests, white oak forests and northern and southern mixed evergreen forests. Although it normally occurs at altitudes below 700 meters up to 100 km inland from the Pacific , it occasionally grows up to 1,500 meters in southern California.

The caterpillar of the tooth moth Phryganidia californica ( English California oak moth , German  Californian oak moth ) lives exclusively on living and fallen leaves of the California holm oak. In cycles of 8 ... 10 years, the caterpillar appears in sufficient abundance to completely defoliate healthy trees. The trees are growing new leaves, and botanists speculate whether the tree, as well as a species of bird or soil creature , might have benefited from this million-year-old coevolution . The California holm oak is also the only known food plant for the caterpillars of the palm moth Chionodes vanduzeei .

Allergenicity

Quercus agrifolia's pollen is a severe allergen ; depending on the geographical latitude and altitude, they are released in spring.

Economic use

Historical use

A California holm oak on Rancho Los Encinos in the San Fernando Valley

Acorns are known to be used as a dietary staple food by at least twelve different cultures of the local Indians . In the 18th century, the then immigrant Spaniards in the San Fernando Valley used the wood to extract coal to fire kilns for the production of adobe bricks . Later this charcoal was also used for baking, as well as for the production of gunpowder and electrical energy .

In the 18th and 19th centuries, shipbuilders looked specifically for the oddly angled branches in order to be able to make special connections. Settlers migrating west harvested small amounts of the wood to make farm inventory and wagon wheels, but the biggest tampering with that was clear-cutting of the oak forests to create sprawling cities like San Diego and San Francisco . The irregular shapes prevented the trees from being used extensively for use in construction; they let the early settlers endow the trees with mystical properties. Her stately appearance made her the subject of historical landscape painting throughout California since the mid-19th century .

Modern use

California holm oaks became a common design element in landscape architecture in the western United States. However, the species is sensitive to changes in soil composition and aeration; In particular, it is necessary to leave the layer of the root crown untouched and not to pour any soil near the trunk during the (landscape) construction work.

When the oaks will be included in a landscape concept with irrigation, it is also important to maintain a regular watering in the eaves of the treetop be avoided, as moist soil in summer, the risk of infection of soil-borne Phytophthora diseases while as the " sudden oak death " ( english sudden oak death ) increase.

Local names

The Californian holm oak, especially its Spanish names encino or encina , encinitas ("small oaks") and encinal ("oak grove"), was named after seven state land allotments across California and by many municipalities and field names.

These include Rancho Los Encinos , the Encino neighborhood in Los Angeles, Encinitas near San Diego and the Encinal del Temescal , which is now part of Oakland .

Paso Robles ('oak pass') also refers to oak as a field name.

Individual evidence

  1. ↑ Quercus agrifolia . United States Department of Agriculture, Natural Resources Conservation Service. Retrieved May 22, 2019.
  2. ↑ Quercus agrifolia . In: Flora of California . Retrieved May 22, 2019.
  3. ↑ Quercus agrifolia . iucnredlist. 2016. Retrieved November 21, 2017.
  4. ↑ a b c d e f Kevin C. Nixon: Quercus agrifolia . In: Flora of North America @ eFloras.org . Retrieved May 22, 2019.
  5. ↑ Luis Née: Anales de Ciencias Naturales , Volume 3 (9) 1801.
  6. ↑ Quercus agrifolia . The Plant List. Retrieved May 22, 2019.
  7. ↑ Luis Née: Descripción de varias especies nuevas de 'Encina' (Quercus de Linneo). . In: Anales de historia natural , Volume 3 1801.
  8. ^ Leonard Plukenet: Phytographia [... Pars tertia] 1692.
  9. ^ Leonard Plukenet: Almagestum botanicum 1696.
  10. ↑ (Oak) Notes . In: Trees of Stanford & Environs . Retrieved May 23, 2019.
  11. ^ Coastal Live Oak (Quercus agrifolia) . In: PollenLibrary . Retrieved May 23, 2019.
  12. ^ Daniel Moerman: Native American Food Plants: An Ethnobotanical Dictionary . Timber Press, 2010.
  13. ↑ JM Davidson: Sudden Oak Death and Associated Diseases Caused by Phytophthora ramorum . Plant Management Network. July 7, 2003. Retrieved January 12, 2010.
  14. ^ Erwin Gudde, William Bright: California Place Names , 4th Edition, University of California Press, 1998, ISBN 0-520-21316-5 .

Other sources

  • Balls, EK (1972). Early Uses of California Plants . University of California Press, Berkeley.
  • Pavlik, BM, Muick, P., Johnson, S., & Popper, M. (1991). Oaks of California . Cachuma Press ISBN 0-9628505-1-9 .
  • Sawyer, John O., & Keeler-Wolf, Todd. (1995) A manual of California Vegetation. California Native Plant Society, p. 241.

Web links