Centro de Ciências Biológicas e da Natureza, Universidade Federal do Acre

Professor, Department of Botany & Rocky Mountain Herbarium, University of Wyoming

Professor of Genomics, Evolution and Bioinformatics, Arizona State University

Full Professor in Systematic Botany, PLANTSEED Lab, University of Pisa

IICAR-CONICET - Cátedra de Botánica, Facultad de Ciencias Agrarias, UNR

Curator, New York Botanical Garden

Real Jardín Botánico CSIC

UC Foundation Professor, University of Tennessee at Chattanooga

Associate Scientist, Florida Museum of Natural History, University of Florida

Universidade Federal de Pernmabuco