FAGALES

the beech order of flowering plants (angiosperms, or Magnoliophyta), belonging to the class Magnoliopsida (dicotyledons; characterized by two seed leaves), subclass Hamamelidae. It consists of three families and some 1,100 to 1,200 species. The Fagales are all woody trees and shrubs with simple leaves usually arranged alternately. The most distinguishing feature is the cupule (hull) subtending or surrounding the fruit or nut. Male flowers appear as catkins on the same tree with the female flowers, which are arranged singly or in clusters and subtended by a whorl of scales that forms the cupule. Most Fagales are native to temperate and subtropical regions, but many speciesnotably those of the birch family (Betulaceae)reach the growing limits for woody plants in the Arctic and Alpine climatic zones. The smallest family in the order, Balanopaceae, consists of only one genus, Balanops, with about 9 species. Its distribution is restricted largely to New Caledonia in the southwestern Pacific Ocean. The family Betulaceae contains 6 genera and about 120 to 150 species. The genus Betula (the birches), with about 60 species, is the largest in the family. The family is widespread in the Northern Hemisphere, with only members of the genus Alnus (alders) extending into the Southern Hemisphere. The genus Corylus produces the edible filbert, or hazelnut. By far the largest family in the order is Fagaceae (the beech family), with 9 or 10 genera and some 1,000 species; the genus Nothofagus, the false, or southern, beech, sometimes is classified as a separate family within the order Fagales. Prominent genera within the Fagaceae include Fagus (beeches), Castanea (chestnuts and deciduous chinquapins), Castanopsis (evergreen chinquapins), Lithocarpus (including the tanbark oak), and Quercus (oaks). Quercus contains the largest number of species (about 450), followed by Lithocarpus (some 300 species) and Castanopsis (120 species). Members of the family are distributed largely in the Northern Hemisphere, with the greatest species diversity found in East and Southeast Asia and North America; the genus Nothofagus is restricted to the Southern Hemisphere. beech order of dicotyledonous woody flowering plants, a division of the subclass Hamamelidae. Additional reading Useful material is offered in B.S. Fey and Peter K. Endress, Development and Morphological Interpretation of the Cupule in Fagaceae, Flora (Jena), 173(56):451468 (1983). Also of interest is Peter K. Endress, Evolutionary Trends in the Hamamelidales-Fagales Group, in Plant Systematics and Evolution, Supplementum, vol. 1 (1977), pp. 321347, a very good account of similarities, with many clarifying illustrations.