A phenetic study of Crepis tectorum in Fennoscandia and Estonia

摘要

Morphological variation inCrepis tectorumin Fennoscandia and Estonia was assessed in a multivariate study of herbarium material. The variation pattern revealed was more complex than that detected in earlier studies of the species in this area. There was a gradual transition between the common weed form and a similar form occurring on rocky outcrops throughout the area, particularly along the coasts and on steep hillsides on the mainland. The two endemic alvar forms on the Baltic islands of Oland and Gotland were distinct from each other but overlapped slightly with other groups. An additional outcrop form from the coast of South Finland graded into the Oland alvar form while the alvar form from Gotland was more similar to the widespread forms on the mainland of Fennoscandia and in Estonia. An outgroup comparison suggested that the widespread forms on the mainland have retained a more “ancient” morphology than the geographically restricted Baltic forms. Morphological and distributional data are used to test and extend earlier hypotheses regarding the evolution ofC. tectorumin these areas. An eastern route seems likely for the first immigrations of the species into Fennoscandia. I suggest that the Baltic forms and at least some populations of the weed form were derived from non‐weedy outcrop populations on the mainland, the first group when the Baltic lowland areas emerged from the sea, and the second group when man created suitable conditions for weed colonizations throughout Fennoscandia. Taxonomic implications of the results are also disc