Affiliation: | 1. Department of Botany, University of Reading, Whiteknights, P.O. Box 221, Reading RG6 2AS, UK Author for correspondence, permanent address: Real Jardi´n Bota´nico, c/ Claudio Mollano, s. n., 28014-Madrid, Spain.;2. Department of Botany, University of Reading, Whiteknights, P.O. Box 221, Reading RG6 2AS, UK |