Southwest Desert Flora

Fagaceae, Beech and Oak Family

The Fagaceae, also known as the Beech Family is a family with approximately 9 genera and 1,101 accepted species names. The largest 3 genera in the family make up almost 98% of the total species and includes the largest genus Quercus (597) species, the second largest genus Lithocarpus (336) species and finally the genus Castanopsis (140) species. The genus Quercus is native to the Northern Hemisphere from cool temperate climates to tropical latitudes in the Americas, Asia, Europe and North Africa. Lithocarpus species are all native to Southeast Asia and members of the genus Canstanopsis are found in tropical and sub-tropical climates found in Asia, China, Indochina to Indonesia and Taiwan and Japan.

The Fagaceae may not be the largest family however it does include some of the most important woody plants both in biomass and economic opportunities including uses for lumber, firewood and commercial cultivation. The fruits, (nuts) are eaten by small mammals and humans eat the chestnuts. The are also important as the dominant and keystone species in forests, woodlands and chaparral. The trees and shrubs provide some of the best habitat for a variety of wildlife species and they provide excellent habitat for a multitude of insects. The largest genera in North America and the Western Hemisphere providing outstanding economic important is Quercus. Mexico also has the largest number of Quercus species with at least 125 species. The southeastern United States is a secondary area of diversity for Quercus.

Family Characteristics: Evergreen trees and shrubs, leaves leathery or tough, alternate, simple leaves with pinnate venation, some spirally arranged; leaf margins may be entire, toothed or lobed, both petioles and stipules are generally present; flowers unisexual, male flowers borne in erect catkins. One of the most recognizable family characteristic is the presence of nuts which include the acorn, chestnut and beechnut.

Important species: The family is considered to be one of the most ecologically important woody plant families in the Northern Hemisphere. Oaks are truly the backbone of temperate forests in North America, Europe, and Asia and one of the most significant sources of wildlife fodder. The true Oaks of the genus Quercus provide the most important resources to the economy. Oak wood is very dense and highly resistant to insect and fungal attack with its high tannin content. Products make from oak wood include the construction of fine furniture, ship building, public buildings and wine barrels. Japanese oak is used in the making of professional drums from the manufacturer Yamaha Drums and the bark of cork oak is used to make wine bottle stoppers. Of the North American oaks, the northern Red Oak is one of the most prized of the red oak group for lumber but the White Oak, Q. alba, sets the standard for lumber production. The American Chestnut, Castanea dentata, was devastated by "chestnut blight", an actinomycete fungus. Many species are valued as ornamentals.

Today, many species of oaks are under threat of extinction in the wild because of habitat loss and harvesting for lumber at unsustainable rates. In the eastern United States rare species of oaks include the Scarlet Oak Q. coccinea, Chinkapin Oak, Q. muehlenbergii, and the Post Oak, Q. stellate. The leaves and acorns of the oak tree are poisonous to cattle, horses, sheep, and goats in large amounts due to the toxin tannic acid, and cause kidney damage.

Species of the genus Lithocarpus are commonly known as the “stone oaks and are very attractive ornamental trees, frequently are used in parks and large gardens in warm temperate and subtropical areas. The genus Castanopsis can inhabit a wide range of temperate to tropical habitat and are often keystone species in their ecosystems.

In North America, according to the USDA Plants Database, there are over 106 species of Quercus. This number does not include the number of hybrid species which would include another 100 species or more.

In addition to the true oaks, other native, non-hybrid species found in North America include American Beech, Fagus grandifolia; American Chestnut, Castanea dentata; Chinquapin C. pumila; Bush Chinqupin, Chrysolepis sempervirens; Giant Chinquapin, C. chrysophylla; and Tanoak, Notholithocarpus densiflorus.