Variation in floral characters, particularly florascent, in sapromyophilous Stemona species

Flowers or inflorescences often deploy varioussignals, including visual, olfactory, and gustatory cues,that can be detected by their pollinators. In many plants,these cues and their functions are poorly understood.Deciphering the interactions between floral cues andpollinators is crucial for analyzing the reproductivesuccess of flowering plants. In this study, we examinedthe composition of the fetid floral scents produced byseveral Stemona species, including nine S. tuberosapopulations from across China, using dynamic headspaceadsorption, gas chromatography, and mass spectrometrytechniques. We compared variations in floral phenotype,including floral longevity, nectar rewards, pollinatorbehavior, and flower length and color among theStemona species. Of the 54 scent compounds identified,the major compounds include fetid dimethyl disulfide,dimethyl trisulfide, 1-pyrroline, butyric acid, p-cresol,isoamyl alcohol, and indole. We detected strikingdifferentiation in floral scent at both the species andpopulation level, and even within a population of plantswith different colored flowers. Floral characteristicsrelated to sapromyophily and deceptive pollination,including flower color mimicking livor morris and a lackof nectar, were found in five Stemona species, indicatingthat Stemona is a typical sapromyophilous taxon. Speciesof this monocot genus might employ evolutionary tacticsto exploit saprophilous flies for pollination.