1. M. J. Y. Foley, Faraday Building, Department of Biological Sciences, University of Lancaster, Lancaster, LA1 4YA, U.K.; e-mail: m.foley@lancaster.ac.uk
2. I. C. Hedge & M. Möller, Royal Botanic Garden, Inverleith Row, Edinburgh, EH3 5LR, U.K.; e-mail: i.hedge@rbge.org.uk, m.moeller@rbge.org.uk