Trochodendrales

Trochodendrales is an order of flowering plants recognized in the APG IV classification, containing a single living family, Trochodendraceae, as its only representative. The family consists of two living genera, each with a single species, native to southeast Asia, along with several extinct genera known from the fossil record. Both living species share the unusual trait of secondary xylem lacking vessel elements, a primitive wood structure that is rare among flowering plants and has made the order significant for the study of early angiosperm evolution.