Pyrola asarifolia in North America exhibits both habitat-correlated variations and a tendency towards regional differentiation in eastern and western populations. Multivariate analysis of morphological characters and chromatographic analysis of leaf flavonols reinforce the view based on traditional taxonomic evaluation that members of the P. asarifolia complex (P. asarifolia, P. bracteata, and P. californica) are best regarded as elements of a single polymorphic species, P. asarifolia. Of the various segregates and infraspecific taxa included in this complex, only the large-bracteate specimens from the Pacific Northwest are sufficiently distinct to warrant taxonomic recognition. They reflect the regional differentiation of P. asarifolia in western North America towards a more robust growth form and oval leaf blade shape. Their status as a distinctive geographical element is recognized in the new combination, Pyrola asarifolia subsp. bracteata. One of the main areas of taxonomic difficulty in Pyrola occurs in sect. Pyrola (see Kiisa 1971 for sectional subdivisions). The type of the section is P. rotundifolia L., a white-flowered species common throughout Europe and eastward to just beyond Lake Baikal in Siberia (cf. Hulten 1958, map 123). Numerous taxa, both whiteand pink-flowered, have been recognized as segregates of this widespread species, or described as distinct species but related to P. rotundifolia. In North America, the taxa of sect. Pyrola that have been given the widest recognition in current manuals and floras are P. americana Sweet, P. asarifolia Michaux, P. bracteata Hook., and P. grandiflora Radius. The similarity between the North American and Eurasian members of this section have been discussed by Fernald (1904, 1920), Andres (1912), and Hult6n (1958). In a more recent study, Krisa (1966) evaluated the specific limits in P. asarifolia, P. americana, and P. bracteata by analyzing the measurement data of several key characters commonly used to distinguish the taxa. He proposed as a consequence a new segregate taxon, P. californica Kirisa. The three pink-flowered taxa examined in this study of the P. asarifolia complex in North America are the common transcontinental species P. asarifolia and two putatively distinct species from the Rocky Mountains and the Pacific region, P. bracteata and P. californica. The recognition of P. californica was based mainly on slight differences in character means that were presumed to be distinct. The data, summarized mainly as polygonal graphs and scatter diagrams, unfortunately were not accompanied by a measure of variance that could be used to determine whether significant differences in character means existed between P. asarifolia and P. californica. The present study is an extension of previous work documenting the variability of the eastern North American species of Pyrola (Haber 1971). It was initiated because there was an obvious morphological similarity and character state overlap between P. asarifolia and P. californica, which suggested that the latter was a doubtfully valid segregate. A more objective evaluation of character means and a critical look at habitat-correlated variation was required. Emphasis was first placed on determining the presence and extent of regional variation in geographically delimited samples of P. asarifolia from across its range. The degree of habitatcorrelated variation was examined, particularly as it related to the recognition of the wetland segregate P. asarifolia var. purpurea (Bunge) Fernald. Once an understanding of the variability of P. asarifolia s.str. had been gained, P. bracteata and P. californica were then compared with P. asarifolia in terms of their range, habitat preferences, consistency of character expression, and leaf flavonols. A multivariate analysis technique was also used to evaluate character variation among the three taxa. The affinity of the asiatic taxon P. incarnata (DC.) Fischer ex Komarov to P. asarifolia was also considered in the