Roridin A (1) and verrucarin A (2), inhibitors of pollen development in Arabidopsis thaliana, have been isolated from the fungus Cyclindrocarpon sp. They inhibited the pollen development at concentrations of 2 and 20 muM, respectively. The microscopic examination of pollen development suggested that the inhibition by the treatments with them was at the microspore stage. (C) 2004 Elsevier Ireland Ltd. All rights reserved.