Secondary metabolites serve multiple functions in plants and play a key role in many ecological processes. Accordingly the quantification of such compounds is central to addressing many questions in plant science. Alongside precision analytical methods like gas and liquid chromatography-mass spectrometry there exists a substantial niche for inexpensive and rapid spectrophotometric approaches if their usefulness in a system can be demonstrated. This study seeks to examine the utility of two commonly used colorimetric methods ' the Folin-Ciocalteu assay and the aluminum complexation assay ' for quantifying variation in leaf phenolic and flavonoid content among members of the genus Helianthus the sunflowers. Among species known a priori to vary substantially in both the diversity and relative concentrations of secondary metabolites both assays detect substantial variation among species. Moreover total phenolic content as assessed by the Folin-Ciocalteu assay correlates positively with concentrations of multiple individual phenolic compounds as quantified by high performance liquid chromatography-mass spectrometry indicating that the Folin-Ciocalteu describes variation in sunflower phenolic content. Additionally the diversity of flavonoids known from Helianthus include a number of those known to be sensitive to the aluminum complexation assay indicating that this assay may also be a useful descriptor of relative variation in sunflower flavonoid content. In total both the Folin-Ciocalteu and aluminum complexation assays appear to capture useful if coarse variation in secondary metabolites among Helianthus species and seem useful as rapid low-cost methods for exploratory research preliminary analyses and potentially useful for high-throughput phenotyping within wild or cultivated sunflower with proper calibration.