The two living species (Tetracentron sinense and Trochodendron aralioides) both have secondary xylem without vessel elements, which is quite rare in angiosperms.

[2] A diverse assemblage of trochodendraceous species have been described from the Eocene Okanagan Highlands in British Columbia and Northeastern Washington.

The monotypic genera Paraconcavistylon and Pentacentron are accompanied by Tetracentron hopkinsii and the Trochodendron infructescence morphospecies Tr.

In previous systems they have been related with the Cercidiphyllaceae and the Eupteleaceae, with which they share some characteristics that can be considered symplesiomorphic or convergent and that have been excluded from the order Trochodendrales because of molecular data leaving the Trocodendraceae isolated.

Based on molecular and morphological data, the APW (Angiosperm Phylogeny Website) considers that it constitutes the only family in the Order Trochodendrales (cf.

The Cronquist system, of 1981, accepted both Trochodendraceae and Tetracentraceae as families and placed these in the order Trochodendrales, in subclass Hamamelidae, in class Magnoliopsida.