A multivariate morphological analysis of the Cardamine concatenata alliance (Brassicaceae) PATRICK W. SWEENEY 1 AND ROBERT A. PRICE Sweeney, P. W. & R. A. Price (Botany Department, The University of Georgia, Miller Plant Sciences, Athens, GA 30602, U.S.A.). A multivariate morphological analysis of the Cardamine concatenata alliance (Brassicaceae). Brittonia 53: 82- 95. 2001.--Principal coordinate analysis using Gower's similarity coefficient and canonical discriminant analysis were performed using morphological data to as- sess species distinctness in the Cardamine concatenata alliance, comprising the eastem North American dentarias. The results of an overall principal coordinate analysis of the alliance using quantitati~ee and qualitative characters revealed dis- tinct and separate clusters that correspond to five previously recognized species (C. angustata, C. concatenata, C. diphylla, C. dissecta, C. maxima). One addi- tional taxon, C. incisa, was found to group closely with the C. diphylla cluster. In a second principal coordinate analysis including only individuals from C. di- phylla and C. incisa, both are supported as distinct morphological entities. Ca- nonical discriminant analysis of only above-ground quantitative characters was less effective in distinguishing previously recognized taxa, in keeping with the emphasis on qualitative characters in previous taxonomic treatments of the group. Cardamine incisa (Eames) Schumann (pro hybr.) is raised to the rank of species. A key to the species of the Cardamine concatenata alliance is provided. Key words: Brassicaceae, Cardamine concatenata alliance, Dentaria, Carda- mine incisa, principal coordinate analysis, morphological species. Introduction The Cardamine concatenata (Michx.) O. Schwarz alliance is a distinctive group of perennial species occupying rich deciduous forest habitats in eastern North America. All members are morphologically similar, possessing an elongated fleshy rhizome and ternately to palmately compound leaves. The alliance is strongly supported as mono- phyletic, by a study utilizing parsimony analysis of DNA sequence data from the chloroplast trnL intron and ndhF gene (Sweeney & Price, 2000). Species belong- ing to this alliance and other species with thickened rhizomes from western North America and Eurasia previously have been placed in the genus Dentaria L. (e.g., see 1Current address: Biology Dept., University of Mis- souri-St. Louis, 8001 Natural Bridge Rd., St. Louis, MO 63121. Fernald, 1950; Harriman, 1965; Wofford, 1989). However, molecular sequence data suggests that the eastern North American, western North American, and Eurasian den- tarias have arisen separately from within Cardamine (Franzke et al., 1998; Sweeney & Price, 2000). Thus we include Dentaria within Cardamine L., as has been suggested on morphological gro.unds by individuals treating the genus on a wider geographic basis (e.g., A1-Shehbaz, 1988a, 1988b; Jones & Akeroyd, 1993; Rollins, 1993). The distributions of the previously rec- ognized species in the alliance vary from widespread to quite restricted (Harriman, 1965; A1-Shehbaz, 1988b; Rollins, 1993; Sweeney, 1999). Cardamine concatenata (Michx.) O. Schwarz (=Dentaria laciniata Muhl.) has the widest distribution, being found from Quebec and Ontario to Minne- sota, and south to Florida through Texas. Brittonia, 53(1), 2001, pp. 82-95. ISSUED: 15 May 2001 9 2001, by The New York Botanical Garden Press, Bronx, NY 10458-5126 U.S.A.