A small order of flowering plants, division Magnoliophyta (Angiospermae), which gives its name to the subclass Hamamelidae in the class Magnoliopsida (dicotyledons). The family Hamamelidaceae contains about 100 species and the Platanaceae about 6 species; the other 3 families have only 2 species each. Within its subclass, the order is more advanced than the Trochodendrales in having vessels in the wood, but less advanced than the other orders in that the gynoecium consists either of separate carpels or of united carpels that open at maturity to release the seeds. Witch hazel (Hamamelis; see illus.), sweet gum (Liquidambar, family Hamamelidaceae), and the plane tree or sycamore (Platanus) are familiar members of the Hamamelidales.