Morphological variation in Scandinavian populations of the diploid-tetraploid species pair Anthericum ramosum and Anthericum liliago (Anthericaceae)

Both members of the diploid-tetraploid species pair Anthericum ramosum L. and Anthericum liliago L. occur as geographically disjunct isolates on the margins of their northern range in Scandinavia. Variation in floral morphology was studied in 33 populations of A. ramosum from four geographic regions and 25 populations of A. liliago from seven regions in Scandinavia. Tepal shape was characterized with the help of moment invariants, and intra- and inter-specific variation in style and filament length was investigated. There were significant between-region and between-population differences in tepal shape and style and filament length within both species. However, despite the geographic disjunction of both species' distributions, there was considerable overlap in tepal shape between populations from the different regions. The hierarchical partitioning of tepal shape diversity was similar in the two species. Most of the total diversity was explained by regional and interpopulation components of diversity (48% and 35%, respectively, in A. ramosum and 61% and 22%, respectively, in A. liliago). The two species were clearly discriminated on the basis of tepal shape and style and outer filament lengths. A southern Swedish population, containing triploid hybrids between A. ramosum and A. liliago, was indistinguishable from other Scandinavian populations of A. liliago on the basis of tepal shape. However, a (allegedly hybrid) Danish population of A. liliago was intermediate between the two species in tepal shape.