4c. Sudden Oak Death

Tanoak, formerly known taxonomically as Lithocarpus densiflorus, was recently moved into a new genus, Notholithocarpus, based on multiple lines of evidence.

Lithocarpus is a genus in the beech family Fagaceae, differing from Quercus in the erect male spikes. The World Checklist (see link below) accepts 334 species, though some other texts suggest as few as 100 species. About 100 Asian species of the genus were formerly treated in the genus Pasania. All but one are native to east and southeast Asia; the single exception, L. densiflorus, Tanoak, being native to western North America in southwest Oregon and California. The Asian species do not have a well-known English vernacular name, though the generic term stone oak has been proposed.

Although normally included in Lithocarpus, recent genetic evidence suggests that the North American species is only distantly related to Asian species; it may be better transferred to a genus of its own.

They are evergreen trees with leathery, alternate leaves, which may be either entire or toothed. The seed is a nut very similar to an oak acorn, but with a very hard, woody nut shell (hence the genus name, from Greek lithos, stone, + carpos, seed). The nut kernel is edible in some species (e.g. Lithocarpus edulis), but inedible, and very bitter, in others (e.g. L. densiflorus).

Several of the species are very attractive ornamental trees, used in parks and large gardens in warm temperate and subtropical areas.

The family Fagaceae, or beech family, comprises about 900 species of both evergreen and deciduous trees and shrubs, which are characterized by alternate simple leaves with pinnate venation, unisexual flowers in the form of catkins, and fruit in the form of cup-like (cupule) nuts. Fagaceous leaves are often lobed and both petioles and stipules are generally present. Fruits lack endosperm and lie in a scaly or spiny husk that may or may not enclose the entire nut, which may consist of one to seven seeds. The best-known group of this family is the oaks, genus Quercus, the fruit of which is a non-valved nut (usually containing one seed) called an acorn. The husk of the acorn in most oaks only forms a cup in which the nut sits.

Several members of the Fagaceae have important economic uses. Many species of oak, chestnut, and beech (genera Quercus, Castanea, and Fagus respectively) are commonly used as timber for floors, furniture, cabinets, and wine barrels. Cork for stopping wine bottles and a myriad of other uses is made from the bark of cork oak, Quercus suber. Chestnuts, a tasty treat enjoyed by many in the winter, are the fruits from species of the genus Castanea. Numerous species from several genera are prominent ornamentals, and wood chips from the genus Fagus are often used in flavoring beers.