Progress Report On Helichrysum LanceolatumHelichrysum lanceolatum (Asteraceae) is an endemic shrubby daisy species widespread in New Zealand. It is often found at disturbed sites such as road cuttings, track margins, and river banks. Allan recognised three varieties in his New Zealand Flora Vol. I treatment, a widespread form with small leaves and unbranched inflorescences, and two large leaved forms with branched inflorescences from Northland and offshore islands, but Webb treated all as a single entity for Flora v. IV. The late Tony (A.P.) Druce thought that plants from Paerutu (Surville Cliffs) were potentially distinct on account of their trailing habit and he also highlighted a particularly large round leaved form from Hick’s Bay as distinctive.
It has been clear for some time that H. lanceolatum is misplaced, under current concepts, in the genus Helichrysum, but unclear whether the species can be accommodated in an existing New Zealand genus, or should be treated as a new monotypic genus. The species was originally named as Swammerdamia glomerata Raoul, but this name is not appropriate, as the type species of Swammerdamia is an Australian species long treated as part of Ozothamnus and not closely related to H. lanceolatum.
We have used molecular data to test whether distinctive populations of H. lanceolatum fit expectations of distinct species or subspecies or whether they represent extreme ends of a single, albeit variable, entity. New Zealand Department of Conservation (DOC) staff Peter de Lange and Cathy Jones contributed samples to our study and other DOC staff helped with collection permits and liaison with Tangata Whenua, for which we are grateful. AFLP data for 45 samples covering a good part of the North and South Islands are consistent with a broad concept of H. lanceolatum, with a major part of genetic variation explainable by increasing genetic isolation between populations as a result of geographic distance (in other words, a cline). This work has been written up and submitted to New Zealand Journal of Botany. We will not be recognising any formal sub-specific taxa.
At the generic level, H. lanceolatum is linked by some molecular data to another taxonomically problematic New Zealand endemic, Ewartia sinclairii (the species of which is referred by the NZPCN to the monotypic genus Ewartiothamnus Anderb.). Before we apply a new genus name to H. lanceolatum, we need to further explore the nature of its link to E. sinclarii and see if they can be accommodated in a single genus. We hope to have this issue resolved within a year.