1. ZMBP, Entwicklungsgenetik, Universität Tübingen, Auf der Morgenstelle 1; D-72076 Tübingen Germany
2. University of Köln, Botanical Institute III, Gyrhofstrasse 15; D-50931 Köln Germany
3. Department of Biological Sciences, University of Alabama, 301 Biology; Tuscaloosa AL 35487-0344 USA
4. Department of Biology, Colorado State University; Fort Collins CO 80526 USA