WARD, JOSEPHINE M.1* and ILSE BREITWIESER2. 1Department of Plant and Microbial Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand; 2Landcare Research, P. O. Box 69, Lincoln 8152, New Zealand. - Intergeneric hybrids in New Zealand Gnaphalieae (Compositae).
Gnaphalieae in New Zealand comprises an estimated 70 to 80 species in
ten genera. Most species, and three of the genera, are endemic. All
genera were earlier included, at least in part, in Gnaphalium
or Helichrysum with the exceptions of Rachelia, which is
newly described, and Craspedia, which belongs to a quite
different alliance. Interspecific hybrids are not infrequent in the
New Zealand flora, but reports of intergeneric hybrids are rare except
in Gnaphalieae, for which a surprising number of anecdotal reports
exist, many of them supported by herbarium material. We report here on
the first rigorous testing of these hybrid hypotheses. Putative
intergeneric hybrids were located in the wild. Four alternative
hypotheses were tested for each specimen: that it was (a) within the
range of variation of an existing species, (b) a mutant form of an
existing species, (d) a hybrid, but of different parentage to that
postulated. Specimens shown to fit none of these hypotheses were
analyzed for intermediacy between the putative parent species,
proximity to one or both parents, and fertility. Artificial
resynthesis was attempted. Results of the analyses of two putative
hybrids are presented. The existence of such putative intergeneric
hybrid links led us to hypothesize that most New Zealand species
evolved very recently within New Zealand rather than arriving
separately by long distance dispersal from several sources. These
would include the species of Anaphalioides, Leucogenes,
Rachelia, Raoulia, those currently retained in
Ewartia and Helichrysum, and possibly Euchiton,
but not Ozothamnus or Pseudognaphalium. Indepedent
support for this hypothesis has come from a recent analysis of ITS
sequences which showed the group of all hybridising genera except
Euchiton to be monophyletic.
Key words: Compositae, Gnaphalieae, intergeneric hybrids, New Zealand