The Lobelia polyphylla complex (Campanulaceae: Lobelioideae) comprises small (0.6-2 m tall) polycarpic lactiferous shrubs endemic to the xerophytic dwarf shrub and sclerophyllous shrub regions of Chile (latitude 27-34S), at elevations from sea-level up to 900 (rarely 1200) m. Flowers are quite uniform within the complex: small, unilabiate, dark wine-purple in color, and visited by bees, with anthesis occuring from late winter to early summer (August to February). In contrast, the sessile deciduous leaves and floral bracts show an extraordinary range of variation in size and shape, spanning the entire spectrum from linear laminas 4 mm wide to widely ovate blades nearly 5 cm across. Based largely on this extreme variation in foliar features, a total of 13 species and four varieties referable to the Lobelia polyphylla complex have been described, but botanical opinion has been divided on how many to recognize and at what rank. Wimmer's 1953 treatment in Das Pflanzenreich recognized two species, one of which was subdivided into four varieties plus four heterotypic forms. However, during field work in Chile, this classification proved impossible to implement. To resolve these questions, we performed cluster analyses and principal components analyses on a data set representing 34 morphological characters extracted from 64 specimens, collected throughout the geographic and ecological range of the complex. These analyses supported the recognition of only a single highly polymorphic but undivided species, Lobelia polyphylla. Further, the analyses were unable to detect any correlation between morphological variation and geography, ecology, or elevation.

Key words: Campanulaceae, Lobelia polyphylla, morphological variation, numerical phenetics