Our studies of Oenothera harringtonii (Arkansas Valley Evening Primrose) have revealed geographic variation of floral scent compounds despite evidence of high gene flow. Scent variation in O. harringtonii is mainly associated with a single compound, linalool; which is sometimes found in large quantities. We observe geographic variation in floral scent and have identified two primary chemotypes: SE populations largely lack S-(+)-linalool (linalool -), which is a primary component of the floral bouquet in NW populations (linalool+). We are interested in whether this variation is a result of differential selection across the range - i.e.  high linalool is beneficial in some areas, but not in others. To understand patterns of selection, we need to first ask some important questions: 1) Are floral traits (e.g., fragrance, morphology, nectar) heritable? And if they are 2) Are there differences in gene expression between individuals/plant parts that differ in linalool emission?  This work will involve using specific offspring from the heritability study (those from parents that differ markedly in linalool emission) and fragrance collection, analysis, and comparative transcriptomic work.