New Hyperica For New Zealand and a Reinstated Name
The last treatment of the indigenous hyperica recognised two species H. gramineum and H. japonicum Thunb. ex Murray (Flora IV, 1988) for New Zealand. However, the late Tony Druce had long considered that New Zealand plants treated as H. japonicum were highly variable, and he recognised at one stage as many as four unnamed entities lurking under that name. In some respects this variability was captured in the Flora IV treatment where it was stated that an upland form of H. japonicum apparently confined to the Central Volcanic Plateau of the North Island and the South Island might be distinct, it was event suggested that the this form could be called H. pusillum Choisy.Heenan (2008) has revisited the taxonomy of the New Zealand H. japonicum complex. His work, utilising a combination of molecular (DNA sequence) and morphological data recognises three species within New Zealand H. japonicum; two new endemic species H. rubicundulum Heenan and H. minutiflorum Heenan, and for the plant long believed to be H. japonicum in Australasia, Heenan reinstates the name H. pusillum. His work also shows that H. japonicum – whose type comes from Japan – is not present in Australasia, and that further it is not closely allied to these Australasian species.
Of the two new species, H. rubicundulum is essentially a South Island endemic of montane to alpine tarns (it is known so far from one North Island site in the southern Kaweka Range, within an geographic area from where several other primarily South Island specie, e.g., Rytidosperma corinum are also known to be disjunct to the North Island). Although much of this species habitat is threatened, there are still large parts of this species range where it is abundant and its habitat is protected. Heenan (2008) considers H. rubicundulum as “Naturally Uncommon” using the New Zealand Threat Classification System. The second species, H. minutiflorum is endemic to the Central Volcanic Plateau of the North Island where it grows in ephemeral bogs, on tarn margins and in damp or poorly draining ground in frost flats. Judging by herbarium specimens this species was once very common but as much of its habitat has been lost to pine plantation or invaded by weeds it is now highly threatened, and Heenan (2008) regards it as being “Nationally Critical”.
Hypericum pusillum is widespread through the main islands of New Zealand, though it is apparently absent from the Chatham and subantarctic islands. This species is also in Australia and possibly New Guinea. It is not considered threatened or uncommon. Although highly variable all of the forms when cultivated revert to the typical state.
Fact Sheets for these three species are available on the NZPCN website.
Reference
Heenan, P.B. 2008: Three newly recognised species of Hypericum (Clusiaceae) from New Zealand. New Zealand Journal of Botany 46: 547-558.
Posted: 16/01/2008