About the Authors

W. John Kress

To whom correspondence should be addressed. E-mail: kressj@si.edu

Affiliation Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, D. C., United States of America

David L. Erickson

Affiliation Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, D. C., United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: WK DE. Performed the experiments: DE. Analyzed the data: WK DE. Contributed reagents/materials/analysis tools: WK DE. Wrote the paper: WK DE.