Biogeography of ITS variation in the Helenium autumnale (Asteraceae) species complex

Abstract—We used ITS sequences as species barcodes to evaluate 127 samples of 12 Helenium species from the eastern and central USA, focusing on a species complex of H. autumnale (76 sequences from 11 US states and two Canadian provinces), the federally “threatened” H. virginicum, now recommended for delisiting (30 sequences from three US states), and H. flexuosum (11 sequences from four US states).  ITS sequences confirmed most species identifications and supported the presence of the first population of the “threatened” endemic Missouri-Virginia disjunct, Helenium virginicum, in Indiana.   Because the Indiana plants grow in a restored wetland, have a cpDNA haplotype previously known only from Missouri, with a morphology similar to Missouri variants, and a herbarium search for additional populations in Indiana found none, it is unclear whether the Indiana population is natural or planted.  The presence of a putative sister-lineage to H. virginicum thought to exist on the Bruce Peninsula...