Leather Oak
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''Quercus durata'', commonly known as leather oak, is a species of
oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...
endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
to
California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
, common in the
Coast Ranges The Pacific Coast Ranges (officially gazetted as the Pacific Mountain System in the United States) are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico. Although the ...
and the foothills of the
Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primarily ...
. The common name "leather oak" is derived from the leathery texture on the lop of its
leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
. Taxonomically it is placed in the white oak group (subgenus ''Quercus'', section ''Quercus'').


Description

As described by English horticulturist and botanist
Theodore Payne Theodore Payne (June 19, 1872 - May 6, 1963), was an English horticulturist, gardener, landscape designer, and botanist. His best known work was done over his adult life in Southern California. Biography Payne was born at Manor Farm, Church Brampt ...
, leather oak is "A rather low spreading shrub with rigid branches, foliage rich deep green. Desirable for hillside planting." ''Quercus durata'' is a short species of oak generally growing to in diameter with a height of about . In more extreme cases they have been known to grow to be 3–4 m across. The gray or yellowish twigs have scaly
bark Bark may refer to: * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Places * Bark, Germany * Bark, Warmian-Masurian Voivodeship, Poland Arts, ...
and are about in diameter with the trunk diameter reaching 4–5 cm; the branches can be densely or sparsely distributed. The buds are smooth brown or reddish brown ovals. The
leaf A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...
blades are cupped or convex, rarely somewhat planar; their dimensions are 1.5–3 cm long and 1–1.5 cm broad densely or sparsely distributed along the branches while the margins of the leaves can be entirely or irregularly toothed. The adaxial (upper) surface of the leaves are greenish or yellowish with short semi-erect hairs; the secondary veins are obscure, dense or scattered. The abaxial (lower) surface of the leaves are covered with erect rayed hairs in length that are felty to the touch with prominent secondary veins. The acorns of the leather oak can be found solitary or paired at the end of a small stalk; the cup which encloses up to half of the nut is reddish or yellowish with a scaly texture. The nut itself is cylindrical, measuring 1.5–2.5 cm in diameter and 1–2.5 cm long, the apex can be rounded or obtuse. Because leather oak is a species of white oak, its acorns mature in about 6 months, are hairless inside the acorn shell, and are sweet or slightly bitter tasting; the shell is mildly toxic. It is a
dicot The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, t ...
that flowers in the spring, typically April or May.


Var. ''gabrielensis''

The largest differentiation between the morphology of the ''durata'' variant and the ''gabrielensis'' variant is found in the leaves. The leaves of the ''gabrielensis'' variant are not as densely crowded and still commonly have regular teeth along the edges. The upper surfaces are colored a darker green and are glossy, glabrous (without hair) and usually moderately cupped or sub-planar. The lower surface of the leaves have persistently wooly surfaces with hairs 2–4 mm in length.


Habitat and ecology

The range of ''Quercus durata'' stretches from Shasta County in
Northern California Northern California (colloquially known as NorCal) is a geographic and cultural region that generally comprises the northern portion of the U.S. state of California. Spanning the state's northernmost 48 counties, its main population centers incl ...
to the bottom of the South Coast Range in Santa Barbara County. The most common variant is found in foothill woodlands and
chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranean c ...
ecosystems at elevations between 30 and 1,570 m (100 to 5,150 ft). It is especially abundant in Sargent cypress ('' Hesperocyparis sargentii'') woodlands which can be found in portions of Mendocino, Sonoma, San Mateo, Santa Clara, Monterey, San Benito, San Luis Obispo and Santa Barbara counties as well as the San Francisco Bay region. In more sheltered, inland areas like MacNab cypress ('' Hesperocyparis macnabiana'') woodlands this shrub can extend into riparian zones where summer fogs persist. ''Q. durata'' is well suited for
ultramafic Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed ...
soils which are reddish and typically nutrient poor, having abundant
nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...
,
magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...
, and
chromium Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal. Chromium metal is valued for its high corrosion resistance and hardne ...
content while lacking
calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...
. Ultramafic chaparral communities are found below 500 m (1,500 ft) from Santa Barbara County north through the North Coast Ranges and also within the foothills of the
Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primarily ...
and portions of the
California Central Valley The Central Valley is a broad, elongated, flat valley that dominates the interior of California. It is wide and runs approximately from north-northwest to south-southeast, inland from and parallel to the Pacific coast of the state. It covers ...
. Here, ''Q. durata'' can be found with shrubs including chamise (''
Adenostoma fasciculatum ''Adenostoma fasciculatum'', commonly known as chamise or greasewood, is a flowering plant native to California and Baja California. This shrub is one of the most widespread plants of the California chaparral ecoregion. Chamise produces a specia ...
''), coffeeberry ('' Frangula californica''), buckthorn ('' Rhamnus crocea'') and toyon (''
Heteromeles arbutifolia ''Heteromeles arbutifolia'' (; more commonly by Californian botanists), commonly known as toyon, is a common perennial shrub native to extreme southwest Oregon, California, and the Baja California Peninsula. It is the sole species in the genus ...
''). Scattered occurrences of
canyon live oak ''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 ...
and coast live oak are also found here. In cases outside of serpentine environments, leather oaks typically occur as isolated individuals within a backdrop of plant associations dominated by
California scrub oak ''Quercus berberidifolia'', the California scrub oak, is a small evergreen or semi-evergreen shrubby oak in the white oak section of ''Quercus''. It is a native of the scrubby hills of California, and is a common member of chaparral ecosystems. ...
(''Q. berberidifolia'') and
interior live oak ''Quercus wislizeni'', known by the common name interior live oak, is an evergreen oak, highly variable and often shrubby, found in many areas of California in the United States continuing south into northern Baja California in Mexico. It general ...
(''Q. wislizeni''). The climate in ''Q. durata'' habitat is characterized by of annual precipitation during a wet season of 3 to 8 months, temperatures range from a December low of 30 °F to a July high of 96 °F. It can sustain life in
soil pH Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. Soil pH is a key characteristic that can be used to make informative analysis both qualitative and quantitatively regarding soil characteristics. pH is defined as the neg ...
between 5.5 and 8.3. Based on controlled studies done at
Jasper Ridge Biological Preserve The Jasper Ridge Biological Preserve is a nature preserve and biological field station formally established as a reserve in 1973. The biological preserve is owned by Stanford University, and is located at south of Sand Hill Road and west of Int ...
the harsh environment of ''Q. durata'' limits species after forest clearing or in colonization of grassland at chaparral-prairie boundaries. Low summer precipitation, high solar insolation, and herbivory are the basis for this difficulty rather than germination rates.


''Var. gabrielensis''

Occurs at elevation 370–2,290 m (1,215–7,515 ft) as a limited distribution taxon in the
San Gabriel Mountains The San Gabriel Mountains ( es, Sierra de San Gabriel) are a mountain range located in northern Los Angeles County, California, Los Angeles County and western San Bernardino County, California, United States. The mountain range is part of the Tr ...
within the San Bernardino and
Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world' ...
counties. The dry, exposed slopes of the San Gabriels stretching from La Cañada to
Pomona Pomona may refer to: Places Argentina * Pomona, Río Negro Australia * Pomona, Queensland, Australia, a town in the Shire of Noosa * Pomona, New South Wales, Australia Belize * Pomona, Belize, a municipality in Stann Creek District Mexico ...
are covered in a chaparral with non-serpentine soils suitable for ''Quercus durata var. gabrielensis''. The precipitation, temperature, and soil pH ranges for the ''gabrielensis'' variant are much narrower than the common variant sitting at approximately 24-47 in of water annually, 44-51 °F, and 6.4 to 6.9 pH respectively. The December low in this region is 36 °F while the July high can reach 90 °F.


Biotic interactions

When located close to species of
pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accep ...
, ''Q. durata'' can be infected by certain species of
heteroecious A heteroecious parasite is one that requires at least two hosts. The ''primary host'' is the host in which the parasite spends its adult life; the other is the ''secondary host''. Both hosts are required for the parasite to complete its life cycle ...
rust fungi (''
cronartium ''Cronartium'' is a genus of rust fungi in the family Cronartiaceae. They are heteroecious rusts with two alternating hosts, typically a pine and a flowering plant, and up to five spore stages. Many of the species are plant diseases of major ec ...
)''. Leather oak is a host for the parasitic Gall Wasp ''Cynips washingtonensis'', who deposits its larvae onto the plant and construct small 1–3 mm spherical
gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to be ...
s on ''Q. durata'' as well as
valley oak ''Quercus lobata'', commonly called the valley oak or roble, grows into the largest of California oaks. It is endemic to California, growing in interior valleys and foothills from Siskiyou County to San Diego County. Mature specimens may attain a ...
(''Q. lobata'') and coastal sage scrub oak (''Q. dumosa''). These galls appear in early spring and can be quite numerously attached to twigs and leaves; the gall is typically engulfed in a mass of velvety hairs. Crystalline gall wasp larvae (''
Andricus crystallinus ''Andricus crystallinus'', also known as the crystalline gall wasp, is a species of Gall wasp, gall-forming wasp in the genus ''Andricus''. Its galls are pink and covered in hairs that are white, red, or brown. These galls are often massed togeth ...
)'' can form irregularly shaped, pallidal galls that agglomerate into masses, with individual galls being between 8–9 mm in length. It is also a host plant for the sleepy duskywing (''Erynnis brizo)'' butterfly, which sometimes feeds on nectar, and the Pacific tent caterpillar moth (''Malacosoma constricta''). Birds and small mammals can be attracted to the acorns.


Uses

In a study done by Narvaez et al. in 2000 with a group of goats and sheep at the Hopland Research and Extension Center, it was found that for animals employed in vegetation management programs across grass woodlands and chaparral ecosystems nutritional quality and intake levels of ''Q. durata'' and ''Adenostoma fasciculatum'' foliage were low and demonstrated a need for diet supplementation in livestock performing as part of vegetation control programs. Native Americans peoples used leather oak as a source of food and medicine. After
leaching Leaching is the loss or extraction of certain materials from a carrier into a liquid (usually, but not always a solvent). and may refer to: *Leaching (agriculture), the loss of water-soluble plant nutrients from the soil; or applying a small amoun ...
tannins from the acorns, they would mash it into a nutritional mush that in tandem with other oak products was a staple in their diets. One prevalent leaching method was to place raw acorns in a cloth pouch and leave it in a stream for several weeks to break down. In modern times the mulch from the leather oak is applied to gardens for its efficacy in repelling slugs and grubs. After pupation the oak's gall extracts can be used in tannins and dyes.


References


External links

* * {{Taxonbar, from=Q3827324 durata Endemic flora of California Natural history of the California chaparral and woodlands Natural history of the California Coast Ranges Natural history of the San Francisco Bay Area Natural history of the Transverse Ranges Plants described in 1909 Taxa named by Willis Linn Jepson Medicinal plants of North America Garden plants of North America Drought-tolerant plants