The pollen donor and pollinator attractor hypotheses are non-exclusive alternative explanations for the functions of the staminate flowers of andromonoecious plants. We tested assumptions and predictions of both hypotheses using the andromonoecious perennial Pseudocymopterus montanus (Apiaceae, Apioideae), in which staminate flowers are approximately one-third as massive as perfect ones and sequentially blooming umbels bear varying proportions of staminate flowers. We confirmed that larger umbels receive more visits than smaller ones. We demonstrated that fluorescent dye is a suitable analog of P. montanus pollen and that larger umbels donate more dye to nearby recipient umbels than do smaller ones. We showed that experimental removal of staminate flowers lowers fruit set only in primary umbels. We used stepwise multiple regressions to examine the effects of staminate flowers on xenogamous pollination, overall (xenogamous and geitonogamous) pollination and fruit set. The regressions revealed significant effects of staminate flowers only for cross pollination of primary umbels. We concluded that in P. montanus, staminate flowers function primarily as pollen donors.

1,3,S-Triazapenta-l ,Cdienes of formula Ar-N=CH-N(R)tCH=N-Ar', are a new group of biologically active compounds. Various general methods for their preparation are described and their physical and chemical properties, including stability over range of pHs, are discussed. The unsymmetrical 1,3,5-triazapenta-1,Cdienes (Ar # Ar') are unstable; insolution, particularly, they equilibrate to the corresponding stable symmetrical analogues.Structure-activity relationships in laboratory tests against Boophilus microplus and Tetranychus urticae are discussed. Problems in the synthesis of ring-[14C]amitraz; [ 1,5-di-(2,4-dimethylphenyl)-3-methyl-1,3,5-triazapenta-1 ,Cdiene], an active member of the group, are outlined.

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