The Fagales are an order of flowering plants, including some of the best-known trees. The order name is derived from genus Fagus, beeches. They belong among the rosid group of dicotyledons. The families and genera currently included are as follows:
- Betulaceae - birch family (Alnus, Betula, Carpinus, Corylus, Ostrya, Ostryopsis)
- Casuarinaceae - she-oak family (Allocasuarina, Casuarina, Ceuthostoma, Gymnostoma)
- Fagaceae - beech family (Castanea, Castanopsis, Chrysolepis, Colombobalanus, Fagus, Lithocarpus, Notholithocarpus, Quercus)
- Juglandaceae - walnut family (Alfaroa, Carya, Cyclocarya, Engelhardia, Juglans, Oreomunnea, Platycarya, Pterocarya, Rhoiptelea)
- Myricaceae - bayberry family (Canacomyrica, Comptonia, Myrica)
- Nothofagaceae - southern beech family (Fuscospora, Lophozonia, Nothofagus, Trisyngyne)
- Ticodendraceae - ticodendron family (Ticodendron)
The older Cronquist system only included four families (Betulaceae, Corylaceae, Fagaceae, Ticodendraceae; Corylaceae now being included within Betulaceae); this arrangement is followed by, for example, the World Checklist of selected plant families. The other families were split into three different orders, placed among the Hamamelidae. The Casuarinales comprised the single family Casuarinaceae, the Juglandales comprised the Juglandaceae and Rhoipteleaceae, and the Myricales comprised the remaining forms (plus Balanops). The change is due to studies suggesting the Myricales, so defined, are paraphyletic to the other two groups.
- Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III". Botanical Journal of the Linnean Society. 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x. Archived from the original (PDF) on 2017-05-25. Retrieved 2013-07-06.
- "Royal Botanic Gardens, Kew: Databases and Publications". Archived from the original on 3 February 2004. Retrieved 16 October 2018.