Evolutionary trees are powerful tools used in modern biological research, and commonly used in textbooks and classroom instruction. Studies have shown that K-14 students have difficulties interpreting evolutionary trees. To improve student learning about this topic, it is essential to teach them how to understand and use trees like professional biologists. Unfortunately, few currently used teaching frameworks for evolution instruction are designed for this purpose. In this study we developed the Model of the Use of Evolutionary Trees (MUET), a conceptual model that characterizes how evolutionary trees were used by professional biologists as represented in their research publications. The development of the MUET was guided by the Concept-Reasoning Mode of representation (CRM) model as well as a “model of modeling” framework. The MUET was then used to review instructional and assessment material for K-14 classrooms. Future studies with the MUET may inform the development of teaching materials for K-14 classrooms aimed at improving students' understanding of and learning about evolutionary trees.