Pollination syndrome refers to suites of floral traits that influence biotic or abiotic vectors transporting pollen from one flower to another. These traits typically include flower color, position, shape, size, scent and reward. Scent is a major component of pollination syndrome, as the volatile organic compounds (VOCs) that compose “scent” often attract pollinators or deter predators. The genus Thalictrum in the Ranunculaceae (buttercup family) includes both insect- and wind-pollinated species, enabling comparisons of the role of scent in floral diversification among recently diverged taxa with distinct pollination syndromes. To characterize floral scent, we identified and compared the bouquet of VOCs emitted by insect- and wind-pollination species, as well as by floral vs. vegetative tissue. Scent was collected from tissue samples by traps in a filtered air system, then eluted and analyzed with gas chromatography mass spectrometry. Quantitation and emission rate were calculated to generate floral bouquets. Electroantennograms were performed on selected compounds to examine pollinator response. Focusing on eleven species representative of the two pollination syndromes and spanning the Thalictrum phylogeny, we identified ten key compounds of which five are deterrents against herbivory, two are pollinator attractants, and three have unknown functions. Given that these scent profiles consist primarily of defensive rather than attractive compounds, we hypothesize that repeated transitions from insect- to wind-pollination in Thalictrum may be due to the breakdown of an ancestrally weak insect pollination syndrome. Moreover, scent bouquets appear to follow phylogenetic patterns more so than pollination mode. The variation in distribution of VOCs across species in a phylogenetic framework allows us to test evolutionary patterns of compound co-option during evolution.