A multivariate morphometric study of Aster subg. Doellingeria sect. Triplopappus (Compositae: Astereae) was undertaken to assess the numbers and ranks of taxa that usefully could be recognized. The results of cluster, discriminant, and principal components analyses on a matrix of 362 plants by 11 characters indicated that four species level groups can be recognized: Aster inflrmus, A. reticulatus, A. sericocarpoides, and A. umbellatus. Within A. umbellatus, analyses of a 12-character data matrix on an additional 140 plants and analysis of a second matrix consisting of the data on the 198 plants of the species included in the species-level study supported recognition of two varieties: pubens and umbellatus. The qualitative and quantitative differences between the two varieties were smaller than those among the four species. Using a key to the taxa produced from all results, the distributions of the four species and two varieties were determined from a large sample of herbarium specimens and a nomenclatural synonymy was developed. Some lectotypes and a neotype are designated. All taxa in the section are diploid 2n = 18; chromosome numbers for 42 individuals of A. umbellatus are reported for the first time. Key words: Aster, Doellingeria, Triplopappus, multivariate morphometric study, Aster umbellatus, key.
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