Abstract
The Trillium pusillum Michaux (1803: 215) species complex exhibits a complicated pattern of morphological variability and geographic distributions in southeastern North America (Farmer 2007). In contrast to earlier studies based on isozymes (Cabe and Werth 1995; Timmerman-Erskine et al. 2003), analyses of DNA sequence variability provide evidence of clear boundaries that correspond with morphological and habitat differences to suggest that the group is best recognized as a series of distinct species (Farmer 2007). Species names have been proposed for some of these, and they are recognized as varieties in some taxonomic treatments (e.g. Weakley 2015), but several still are known only from informal designations. One of the rarest, and perhaps most threatened, is the sole representative of the complex in Georgia that is known from only a single creek drainage system in an area being developed for industrial usage. In the current study we provide formal recognition for it, both to emphasize the need to preserve this unique entity, as well as to stimulate searches for further populations of it.