What types of leaves are found among Fagales species?

Species within the order Fagales exhibit a variety of leaf structures, typically arranged alternately along the stem, though opposite or whorled arrangements occur rarely.1

• Simple Leaves: Most Fagales possess simple leaves, which are often deeply lobed or coarsely toothed at the margins in temperate deciduous species. These leaves may be thick and leathery, particularly in evergreen species like those found in the genera Lithocarpus, Chrysolepis, and some Quercus (oaks). In arid habitats, such as those occupied by Casuarinaceae, leaves are reduced to small, scalelike structures arranged in whorls at each node.1
• Compound Leaves: Members of the families Juglandaceae and Rhoipteleaceae are notable for having pinnately compound leaves, which may sometimes be trifoliolate.1
• Adaptations: Leaf characteristics often reflect environmental conditions. For instance, species in dry habitats may feature small, leathery leaves that are spiny or hairy. Additionally, some species, such as beeches, may retain their leaves in a dry state through the winter.1