1. Univ Rennes, CNRS, Géosciences Rennes, UMR 6118 263 avenue du Général Leclerc 35000 Rennes France
2. Department of Geobiology University of Göttingen Goldschmidtstraße 3 37077 Göttingen Germany
3. Mittlere Letten 11 88634 Herdwangen‐Schönach Germany
4. Department of Botany Swedish Museum of Natural History Box 50007 104 05 Stockholm Sweden
5. Institute of Systematic Botany The New York Botanical Garden Bronx New York NY 10458‐5126 USA
6. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Palaeoenvironment Chinese Academy of Sciences 39 East Beijing Road 210008 Nanjing China