Germination Requirements of Lythrum curtissii

Lythrum curtissii is a perennial herb endemic to southwest Georgia, the Florida Panhandle, and northeast Florida. The species is imperiled throughout its range: it is ranked S1 in Georgia, S2 in Florida, and G2 globally. The Jones Center at Ichauway has collected seeds from multiple populations of Lythrum curtissii since 2019 but had achieved little success in germination trials testing different lengths of cold stratification or using gibberellic acid. Using seeds from our living collection, we designed a factorial experiment to test the effects of the duration of cold stratification, flooding, and ambient temperature on germination success. Our results confirm that Lythrum curtissii germinates readily with an alternating 35/20 C day-night cycle. Preliminary results for seeds grown in those ambient conditions suggest that flooded seeds may achieve higher total germination rates than seeds on moist filter paper and that cold stratification might decrease the time required to reach 50% germination.