I thank the Directors of the following herbaria for loans of material and asistance during visits: BK, BKF, BM, C, CMU, E, KUN, L, P, SGN, YUNU. Thanks also to Dr A. Hay and Dr David A. Simpson for helpful comments and suggestions, Mr Alan R. Radcliffe-Smith for translating the diagnosis into Latin and Emmanuel Papadopoulos for the illustrations.