The eudicotyledons or tricolpates are a monophyletic group including all but a few basal dicotyledons. The name tricolpates is preferred under the PhyloCode system. Some authors treat them as a single separate class, the Rosopsida, while others further divide them into several classes. However, this still leaves the remaining dicots (palaeodicotyledons) as a paraphyletic group.

The eudicotyledons are set apart most notably by the production of tricolpate pollen, or forms derived from it. These pollen have three or more pores set in furrows called colpi. In contrast, most other flowering plants and gymnosperms produce monosulcate pollen, with a single pore set in a differently oriented groove called the sulcus.