Valley Oak (LA Urban Forest Program)

Valley Oak

Quercus lobata

Summary ⁸

Quercus lobata, commonly called the Valley oak, grows into the largest of North American oaks. It is endemic to California, growing in the hot interior valleys and foothills. Mature specimens may attain an age of up to 600 years. This deciduous oak requires year-round access to groundwater.

Common names ⁹

valley oak
valley white oak
California white oak
water oak
weeping oak
white oak
roble

Description ¹⁰

General: Oak Family (Fagaceae). California white oak, sometimes referred to as valley oak, is a

deciduous tree, 12 to 30 m tall, with a rounded spreading crown. The mature bark is gray, scaly, and often vertically fissured in a checker-like pattern. Leaves are oblong to obovate, 5 to 10 cm long, with 7 to 11 deep lobes. The upper surface is green and shiny; the lower surface is grayish green. Like all oaks, white oak is monoecious and wind-pollinated. The acorn cups are composed of thick, tubercled scales. The one-seeded nuts are 3 to 5 cm long, oblong to ovoid, and mature in one year. Flowering takes place from March to April. Fruits mature between August and October. Good acorn production has been reported to occur annually, but high acorn numbers occur episodically. Trees of this species may be among the largest oaks in North America.

Description ¹¹

More info for the terms: monoecious, tree

Valley oak is a long-lived, flood- and drought-tolerant, monoecious,
deciduous tree [28.56,53]. It is the largest North American oak
[34,53,61] Trees are typically 30 to 75 feet (10-25 m) tall and from 1.8
to 2.4 feet (0.5-0.7 m) in d.b.h. but may become much larger [13,53]. A
record tree in Gridley measures 9.3 feet (2.8 m) in d.b.h. [13], and
Griffin [30] reported a 138-foot (30 m) valley oak at the Hastings
Natural History Reservation of Carmel Valley. Large oaks are usually
hollow or rotten in the center, making exact age determinations
impossible. Age estimates of very large trees range from 400 to 500+
years [8.30]. Mature stands are typically from 100 to 200 years old
[8].

The crowns of open-grown trees are very broad [30]. Valley oaks have a
highly branched growth habit. The oaks are sensitive to chloride
aerosol, and trees growing less than 4 miles (7 km) inland tend to be
scrubby and flagged [55]. Valley oak typically has several vertical
roots that tap groundwater and extensive horizontal root branches
[28,31]. Vertical root depth has been measured as deep as 80 feet (262
m) in some individuals [45]. Acorns are long (1.2 to 2.0 inches [3-5
cm]) and slender (0.5 to 0.8 inch [1.2-2.0 cm]). The bark is thick and
deeply furrowed [53].

Fuentes y créditos

(c) Zack Abbey, algunos derechos reservados (CC BY), subido por Zack Abbey
(c) Steven J. Baskauf, algunos derechos reservados (CC BY), http://bioimages.vanderbilt.edu/baskauf/66934
(c) 2008 Keir Morse, algunos derechos reservados (CC BY-NC-SA), http://calphotos.berkeley.edu/cgi/img_query?seq_num=270101&one=T
(c) Steven J. Baskauf, algunos derechos reservados (CC BY), http://bioimages.vanderbilt.edu/baskauf/66943
(c) 1998 California Academy of Sciences, algunos derechos reservados (CC BY-NC-SA), http://calphotos.berkeley.edu/cgi/img_query?seq_num=17719&one=T
(c) Alison Young, algunos derechos reservados (CC BY-NC), subido por Alison Young
(c) Philip Bouchard, algunos derechos reservados (CC BY-NC-ND), http://www.flickr.com/photos/62003631@N00/2257572214
Adaptado por earthwatchtrees del trabajo de (c) Wikipedia, algunos derechos reservados (CC BY-SA), http://en.wikipedia.org/wiki/Quercus_lobata
Dominio Publico, http://eol.org/data_objects/23370515
(c) Santa Barbara Botanic Garden & USDA NRCS National Plant Data Center, algunos derechos reservados (CC BY-SA), http://eol.org/data_objects/1392436
Dominio Publico, http://eol.org/data_objects/24643191