The Trillium pusillum Michaux complex consists of five or six morphogeographical taxa distributed within the southeastern United States. A quantitative morphological study was undertaken to determine appropriate species and varietal ranks of these taxa, which have a confused taxonomic history. Numerical analyses based on 14 floral and vegetative characters measured from 29 populations of T. pusillum revealed significant differences among varieties. These exist, however, as arrays of characters rather than as single characters. All characters were highly variable within and among populations, suggesting that quantitative measurements alone are unreliable as distinguishing characters. We concluded that all of the previously recognized infraspecific taxa lack clear morphological separation. We therefore recommend recognition of a single variable species without varietal designations.