Canyon Live Oak

The canyon live oak, known by its scientific name, quercus chrysolepis, is a species of evergreen oak that is found in Mexico and in the western United States, notably in the California Coast Ranges as well as the San Gabriel and San Bernardino mountains.  Also known by the common names canyon oak, golden cup oak or maul oak, the tree, which is confined to North America, 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 rapid identification arises from the leaves of canyon live oak being geometrically flat. They are often sympatric with quercus agrifolia and several other oak species. Fossil data supports a much wider distribution throughout the western United States during the early Holocene period.
Native Americans used the acorns of this species as a food staple, after leaching of the tannins; moreover, its roasted seed is a coffee substitute. After forest fires, canyon live oak regenerates vigorously by basal sprouting, and the clonal diversity of this species has been shown to be high.
This evergreen has significant-sized spreading, horizontal branches, and a broad, rounded crown; it attains a height of 20 to 100 feet and is often found in a shrubby growth form. The trunk diameter can range from 12 to 40 inches. The elliptical to oblong leaves are 1 inch to 3.2 inches in length with widths of about half that dimension. The leaves are short-pointed at the tip, but rounded or blunt at the base. Although the leaves appear generally flat, they may have edge margins slightly turned under, typically with spiny teeth, particularly on young twigs. These leathery leaves are a glossy dark green above, with a nether surface a dull golden down, often becoming gray and relatively smooth the second year.
Bark of the canyon live oak is of a light gray coloration, and ranges from being smooth to rough and scaly. Acorns occur solitarily or in pairs, exhibiting lengths of just under an inch to two inches. They are variable in shape, but generally ovoid, turban-like with a shallow, thick cup of scales densely covered with yellowish hairs; the stalk is barely evident.
Pollination occurs in the spring.
The canyon live oak is found in a variety of forest communities in the southwestern United States. It is common in the mountainous regions of California, including the Sierra Nevada, Coast Ranges, Klamath Mountains, Cascades, San Gabriel Mountains and the San Bernardino Mountains, with additional populations in southwestern Oregon, western Nevada, northern Baja California, Arizona, southwestern New Mexico, and Chihuahua.
Canyon live oak is co-dominant with bigcone Douglas-fir (pseudotsuga macrocarpa) on mesic, steep, north-facing slopes and in ravines in southern California, often within a matrix of chaparral vegetation. It is an important component of mixed hardwood forests and oak woodlands throughout California. It grows in California black oak woodlands in southwestern Oregon and California. Canyon live oak grows with scrub oak (q. dumosa) and island oak (q. tomentella) on Santa Catalina Island and is a component of blue oak (q. douglasii) woodlands in California foothills. It is also associated with Oregon white oak (q. garryana), interior live oak (q. wislizeni), coast live oak (q. agrifolia), and valley oak (q. lobata). Canyon live oak is common in montane and mixed-chaparral communities in the foothills and mountains of southwestern Oregon, California, and northern Baja California  It also occurs in chaparral communities in Arizona. Canyon live oak is also commonly associated with Coulter pine (pinus coulteri) on xeric sites within or adjacent to chaparral in central and southern California and northern Baja California. Canyon live oak is associated with cypress (cupressus spp.) groves throughout California and with bristlecone fir.
Canyon live oak is tolerant of a variety of soil types, including very rocky or cobbly environments. It is hardy to cold temperatures down to −11 °F, and will grow in neutral to moderately acidic soils with pH ranges of 4.5 to 7.5. Canyon live oak grows at elevations of about 1,600 feet to 4,800 feet in southwestern Oregon; in Northern California, from 300 feet to 4,300 feet; and in Southern California, up to approximately 8,200 feet. Quercus chrysolepis can be the dominant tree on steep canyon walls, especially in locations of shallow rocky soils. In areas of moderate to high rainfall, it occurs on south facing slopes, and in the hotter, drier parts of its distribution, on northerly slope faces.
Besides the prehistoric use of canyon live oaks as a human food source, the acorns are consumed by a variety of wildlife as diverse as the acorn woodpecker, California ground squirrel, dusky-footed wood rat, western harvest mouse and black-tailed deer. Surprisingly there seems little difference in food preference by wildlife among different oak species.
Extensive hybridization of quercus chrysolepis has been documented with several other sympatric oak species, probably to a greater extent than for any other quercus species. The ability of canyon live oak to compete with other dominant trees within its range has been analyzed from the standpoint of leaf architecture and photosynthetic capability. The study results explain that, in low light environments, quercus chrysolepis out-competes species with superior leaf size and crown mass per unit volume by its greater photosynthetic efficiency and leaf lifespan.
Canyon live oak gives functional habitat for many fauna by providing perching, nesting, resting, or foraging sites for numerous species of birds, and shade and cover for diverse other mammals. Canyon live oak woodlands serve as excellent mountain lion habitat because of the large population of deer frequenting these areas. Many species forage on canyon live oak foliage including the black-tailed jackrabbit, beaver, brush rabbit, red-backed vole, Sonoma chipmunk, cactus mouse, deer mouse, and porcupine. Pocket gophers often feed on the cambium of young canyon live oaks.
In southern California q. chrysolepis is the food plant of a small moth, Neocrania bifasciata.
The Canyon Live Oak is a severe allergen.
From Wikipedia, and,CA

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