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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]
Oak wilt is a devastating exotic disease, killing some trees rapidly in a single season. [7] Oak wilt is an important disease in urban areas where trees are highly valued. . The disease reduces property values because of the loss of trees and is economically costly to the property owner since they or the local government must pay for tree remo
Although live oaks retain their leaves nearly year-round, they are not true evergreens.Live oaks drop their leaves immediately before new leaves emerge in the spring. Occasionally, senescing leaves may turn yellow or contain brown spots in the winter, leading to the mistaken belief that the tree has oak wilt, whose symptoms typically occur in the sum
Phytophthora ramorum is the oomycete known to cause the disease sudden oak death (SOD).The disease kills oak and other species of trees and has had devastating effects on the oak populations in California and Oregon, as well as being present in Europe.
Quercus turbinella is a North American species of oak known by the common names shrub oak, turbinella oak, shrub live oak, and gray oak. [4] [5] [6] It is native to Arizona, California, New Mexico, Utah, Colorado, and Nevada in the western United States. [4] It also occurs in northern Mexico. [7] Arizona shrub oak acorns. Quercus turbinella.
Q. wislizeni is found in many areas of California [12] in the United States continuing south into northern Baja California in Mexico. It generally occurs in foothills, being most abundant in the lower elevations of the Sierra Nevada, but also widespread in the Pacific Coast Ranges—where since 1980 it has been known as a separate species Quercus parvula [13] [14] —and the San Gabriel Mountains.
Quercus chrysolepis, commonly termed canyon live oak, canyon oak, golden cup oak or maul oak, is a North American species of evergreen oak.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 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. [4] Deciduous, it requires year-round groundwater, [5] [6] and may live up to 600 years.