Quercus wislizeni, known by the common names Interior Live Oak, and Sierra Live Oak, is an evergeen oak

Oak

An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...

, highly variable and often shrubby, found in areas of California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. It also occurs south into northern Baja California

Baja California

Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...

 in Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. It generally occurs in foothills

Foothills

Foothills are geographically defined as gradual increases in elevation at the base of a mountain range. They are a transition zone between plains and low relief hills to the adjacent topographically high mountains.-Examples:...

, being most abundant in the lower altitudes of the Sierra Nevada, but also widespread in the Pacific Coast Ranges

Pacific Coast Ranges

The Pacific Coast Ranges and the Pacific Mountain System are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico...

 and the San Gabriel Mountains

San Gabriel Mountains

The San Gabriel Mountains Range is located in northern Los Angeles County and western San Bernardino County, California, United States. The mountain range lies between the Los Angeles Basin and the Mojave Desert, with Interstate 5 to the west and Interstate 15 to the east...

. It was named for its collector, Friedrich Adolph Wislizenus

Friedrich Adolph Wislizenus

Friedrich Adolph Wislizenus was German-born American MD, explorer and botanist. He is best known of his printed recollections from travels to Northern Mexico and today's state of New Mexico.-Life:...

 (1810–1889).

It is a large shrub

Shrub

A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...

 or tree

Tree

A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...

 growing to 22 m tall. The dark-green leaves

Leaves

-History:Vocalist Arnar Gudjonsson was formerly the guitarist with Mower, and he was joined by Hallur Hallsson , Arnar Ólafsson , Bjarni Grímsson , and Andri Ásgrímsson . Late in 2001 they played with Emiliana Torrini and drew early praise from the New York Times...

 are usually small, 2.5-7 cm long and 2-5 cm broad, thick and often spiny-toothed, particularly on young trees. The flower

Flower

A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...

s are catkin

Catkin

A catkin or ament is a slim, cylindrical flower cluster, with inconspicuous or no petals, usually wind-pollinated but sometimes insect pollinated . They contain many, usually unisexual flowers, arranged closely along a central stem which is often drooping...

s. The acorn

Acorn

The acorn, or oak nut, is the nut of the oaks and their close relatives . It usually contains a single seed , enclosed in a tough, leathery shell, and borne in a cup-shaped cupule. Acorns vary from 1–6 cm long and 0.8–4 cm broad...

s are 1-2 cm long, and mature in about 18 months after flowering.

Ecology

The Interior Live Oak is classified in the red oak section (Quercus sect. Lobatae). Several hybrids between Interior Live Oak and other red oak species have been documented. Hybrids with Coast Live Oak

Coast Live Oak

Quercus agrifolia, the Coast Live Oak, is an evergreen oak , native to the California Floristic Province. It grows west of the Sierra Nevada from Mendocino County, California, south to northern Baja California in Mexico. It is classified in the red oak section Quercus agrifolia, the Coast Live Oak,...

 (Q. agrifolia) are known in many areas in coastal California. It also hybridizes with Nuttall's Scrub Oak

Quercus dumosa

Quercus dumosa is a species of plant in the Fagaceae family. This tree goes by the common name Coastal sage scrub oak.-Distribution:Quercus dumosa is found in Mexico and the U.S. state of California. It is threatened by habitat loss...

 (Q. dumosa) and California Black Oak

California Black Oak

Quercus kelloggii, the California Black Oak, also known as simply Black Oak, or Kellogg Oak, is an oak in the red oak section , native to western North America...

 (Q. kelloggii). All these oak species show evidence of introgression

Introgression

Introgression, also known as introgressive hybridization, in genetics is the movement of a gene from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species...

 with one another. A common alliant tree is California Buckeye, Aesculus californica

Aesculus californica

Aesculus californica is a species of buckeye that is native [ |] to California and southwest Oregon [Jackson, County], and the only buckeye native to these states.-Description:...

.