New variation and biosystematic patterns detected by allozyme and morphological comparisons in Limnanthes sect. Reflexae (Limnanthaceae)

Sixty-one populations of Limnanthes sect. Reflexae were surveyed for variation at 19 allozyme loci and reassessed for their morphological diversity and biosystematic relationships. Cluster analysis of allozyme data at individual population level provided evidence for a fairly good fit with the earlier systematic work on this genus but both morphological and allozyme data together defined some new clusters as well as exceptional entities. For example, only var. rosea of the four L. douglasii varieties described by Mason (1952) on the basis of geographical distribution, flower color and leaf morphology, remained as a distinct entity; the others were realigned along new geographic boundaries. L. striata appeared to have two well-developed subgroups, one of which was closely related to the L. douglasii complex. Further ecogeographic and hybridization studies are needed to fully describe these new phenetic findings in the context of phylogenetic inference. Section Inflexae was readily distinguished from sect. Reflexae by several diagnostic loci, thus supporting the validity of this division. Interspecific variation levels and population differentiation in Limnanthes were high when compared to other plant taxa, possibly indicating highly dynamic evolutionary processes for which variable habitats and extreme subdivision within species have been suggested as explanations.