Several phenolic acids, including p-coumaric acid, have been described as allelochemicals that may inhibit seed germination or seedling growth.  Whether, in forage species, these effects are exacerbated by environmental stressors is not known. Accelerated seed aging (high temperature (41 C) and high humidity (100%)) reduces germination and seedling vigor, and provides some indication as to seed germination and seedling performance under stress conditions (eg., temperature and water stress).  Thus, accelerated aging provides a means to determine how seed "age" might affect germination or seedling vigor in response to a stressor.   Here we compare responses of aged and non-aged seed of crimson clover (Trifolium incarnatum L.) to p-coumaric acid at 10^-5 and 10^-3 M concentrations.  Results indicate that accelerated aging for 24 to 72 h delays and reduces seed germination.  For example, after 72 h (20 C and dark conditions) germination was 95%, 85%, 30%, and 6% for seed aged for 0, 24, 48 and 72 h, respectively.  Germination of non-aged seed was unaffected by the presence of p-coumaric acid.  However, aged-seed germination was further delayed by exposure to p-coumaric, but there was no difference among treatments within a specific accelerated aging treatment.  Preliminary results indicate that accelerated aging delays germination and that this delay is further extended by exposure to p-coumaric acid.