Trevigen's HT Colorimetric PARP/Apoptosis Assay was used to determine the effect of three flavones on PARP-like activity associated with DNA repair in thalli of Marchantia polymorpha exposed to prior UV-C radiation when compared to white light-exposed controls. Thalli placed in solutions of the naturally-occurring flavones apigenin and quercetin showed significantly decreased PARP-like activity after UV-C exposure, but thalli in luteolin solution showed increased PARP-like activity when compared to PBS-treated controls. These effects were not seen with exposure to white light alone when compared to PBS-treated controls. This research is the first to be conducted in bryophytes and suggests a critical control point for PARP-like activity in these organisms.