Whipcord Hebes - systematics, distribution, ecology and evolution

The genus Hebe (Scrophulariaceae) includes 10 species known as whipcords or Flagriformes. Analysis of DNA sequences supports three distinct groups, each with characteristic chromosome numbers and morphology. There is little sequence divergence within these groups, which reflects rapid evolution, perhaps within the last 500 000 years. Two groups comprise montana species of the eastern South Island with chromosome numbers of n = 21. The first includes only H. cupressoides, which diverged early from most other hebes. The second includes H. salicornioides, H. armstrongii, and H. annulata. The third group of whipcord hebes is the largest, has n = 20, and is subalpine-alpine. It consists of H. tetragona and H. hectorii which occupy the wetter mountains along the axial ranges except for a gap of 320 km in central Westland, H. lycopodioides and H. imbricata which occupy drier South Island mountains, and H. propinqua which grows in the south-east of the South Island. H. ochracea from western Nelson appears to be an allopolyploid hybrid between members of the second and third lineages. Based on these results, the following new combinations are made: Hebe hectorii subsp. hectorii, H. hectorii subsp. subsimilis, H. hectorii subsp. coarctata, H. hectorii subsp. laingii, H. hectorii subsp. demissa, H. hectorii subsp. subulata; H. lycopodioides subsp, lycopodioides, H. lycopodioides subsp. patula; H. imbricata subsp. imbricata, H. imbricata subsp. poppelwellii.