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Of the two taxa, P. minor s.s. is more widespread, occurring from the midPuhipuhi River, about 10 km from Kaikoura, north to the true left of the Clarence River, and inland along the Jordan and Wharekiri streams. It occurs predominantly on consolidated gravels and limestone, but also on greywacke rock bluffs of Cretaceous/Jurassic age. Where it occurs it is relatively plentiful, with a full range of size classes from seedlings to mature plants evident. In cultivation at Lincoln this species flowers prolifically, and open-pollinated flowers set abundant seed which germinate readily. On the north bank of the Clarence River the distribution of P. minor s.s overlaps with P. insignis and hybrids occur on two small sites, one each on both banks, on consolidated gravels. In the Puhipuhi River valley it overlaps with a northern outlier of an unnamed taxon referred to as Pachystegia A, but no hybrids have been observed.
At present there is not enough information to assess the threat status of P. minor s.s., but it is unlikely to reach a high threat category. Although one coastal population on limestone at Waipapa Bay has been depleted by quarrying in the past, the main threat to this species is likely to come in the near future from invasion of its habitat by introduced grasses.
In contrast, Pachystegia aff. minor is apparently restricted to a short stretch of coastal greywacke of Cretaceous/Jurassic age from Ohau Point to Black Miller Stream, a distance of about 4–5 km. This particular area is well covered with coastal hardwood forest and scrub and plants of P. aff. minor are relatively few in number, and restricted to scattered bare rock faces.
DOC Science Internal Series 17 In 1985 a significant number of plants of this taxon were destroyed in the realignment of Ohau Point alongside State Highway 1 (Molloy 1985). A few plants have recolonised the fresh rock surfaces since then, but the process is slow. Other threats to the continued well being of this taxon include the likelihood of further remedial roadworks, damage from herbicide used to kill rank grass in roadside water courses, and invasion of its habitat by introduced grasses. Again, there is insufficient information on its full distribution and abundance to assess its threat category, but it is likely to be high.
4. Pachystegia insignis (Hook. f.) Cheeseman This species, illustrated in colour by Eagle (1982, Plate 242) has the widest distribution of all the rock daisies. Northern populations extend from the Clarence River to the Wairau River in coastal districts, and inland to most river catchments draining the northern parts of the Inland and Seaward Kaikoura Ranges, and the Waihopai River and its tributaries further to the north. The species reaches its western limit near Mt Upcot in the Awatere Valley where it overlaps with an unnamed rock daisy referred to as Pachystegia B (Molloy & Simpson 1980). So far no hybrids involving these two taxa have been observed at or near to the point of overlap. A remarkably disjunct southern population of P. insignis occurs south of the Inland and Seaward Kaikoura ranges on the northern slopes of the Lowry Peaks and Hawkswood ranges, immediately south of the Waiau and Conway rivers respectively. The species overlaps with another unnamed taxon referred to as Pachystegia A (Molloy & Simpson 1980) on the Hawkswood Range and putative hybrids have been observed.
Northern populations of P. insignis occur on a range of substrates, including limestone, coastal sands, consolidated gravels, greywacke and volcanics. Most sites support a good range of size classes from seedlings to mature plants and the populations appear relatively stable and self-sustaining. However, riparian populations adjacent to broom-infested riverbeds are especially vulnerable to invasion by broom and introduced grasses, and to herbicides used to control broom and other weeds. Roadside pine plantings tend to shade-out P. insignis, but their effect on these northern populations is relatively minor.
In contrast, southern populations of P. insignis support considerably fewer individuals and are seriously threatened by the invasion of broom which has increased noticeably in the last 20 years or so, especially on slopes above the Waiau and Conway riverbeds, the main source areas of broom. Even more disturbing is the proposal to control these broom infestations by overplanting with exotic conifers. Added to this concern is the probability, as yet unresolved, that these southern populations of P. insignis may prove to belong to a different taxon. Further information on the status of P. insignis in this area is desirable, as these southern populations are most at risk.
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5. Pachystegia A This taxon, as yet unnamed, is illustrated in colour by Eagle (1975, Plate 200, erroneously as P. insignis), and has a well-defined distribution along the coastline from just south of the Conway River north to the Puhipuhi River. Its western distribution inland is, as yet, ill-defined. It overlaps with P. minor s.s.
along the Puhipuhi River with no hybrids evident. It also overlaps with Pachystegia B inland, and with P. insignis on the Hawkswood Range where the question of hybrids is unresolved.
Pachystegia A is found on greywacke, limestone and consolidated gravels throughout its range, usually in well-defined openings in coastal hardwood forests, and is most conspicuous on slopes above State Highway 1 between Oaro and Kaikoura. The population just south of the Kahutara River is vulnerable to broom and introduced grasses, and a temporary loss of habitat occurred with the realignment of the highway at Punchbowl Corner in 1990 (Molloy 1989).
Further temporary loss of habitat is likely with future remedial works, and the significance of this taxon and its native associates has been conveyed to the appropriate authorities accordingly (Molloy 1994).
Despite its somewhat restricted distribution, Pachystegia A is relatively abundant throughout its range, and most populations are highly viable and selfsustainable. Some are fully protected in Crown reserves along this coastline.
I do not consider this taxon to be threatened overall.
6. Pachystegia B This taxon, as yet unnamed, is illustrated in colour by Eagle (1982, Plate 243). It is essentially an inland entity, reaching its northern limit near Mt Upcot in the Awatere valley where it overlaps with P. insignis; and its southern limit in the Leamington Stream, which drains the eastern slopes of the Lowry Peaks Range, North Canterbury. Its eastern and western limits are, as yet, unknown, but it does seem to overlap with Pachystegia A in the southern part of its range.
Hybrids between these two are not evident.
Pachystegia B plants are found on limestone, volcanics, greywacke and, especially, consolidated gravels. These plants are generally smaller than other rock daisies except P. minor with which it has often been confused in the past.
Its small plant size, leaves and flower heads are retained in cultivation and appear genetically fixed. It also is difficult to grow, in contrast with the other taxa. Nevertheless, it is relatively abundant throughout its range, although still susceptible to invasion of its habitat by broom and exotic grasses, and shading from planted exotic conifers. However, I do not regard it as a threatened taxon.
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7. Acknowledgements The support of Cathy Jones, Department of Conservation, Nelson, and Rob McColl, Department of Conservation, Wellington, with this project is acknowledged with thanks. I also thank Cathy Jones, Jan Clayton-Greene, Faith Barber, and Dave Walford, Department of Conservation, Nelson/Marlborough, for field assistance and other information.
The use of the Kingett Mitchell & Associates report is gratefully acknowledged, likewise the use of the live collections of Pachystegia plants held at Landcare Research, Lincoln, and the Christchurch Botanic Gardens. Finally, I thank the staff of the Landcare Research Herbarium, Lincoln, for help with the collection of Pachystegia specimens.
8. References Cheeseman, T.F. 1916: New species of plants. Transactions of the New Zealand Institute 48: 210.
de Lange, P.J. et al. 1999: Threatened and uncommon plants of New Zealand. New Zealand Journal of Botany 37: 603–628.
Eagle, A. 1975: Eagle’s trees and shrubs of New Zealand in colour. Auckland, Collins.
Eagle, A. 1982: Eagle’s trees and shrubs of New Zealand second series. Auckland, Collins.
Molloy, B.P.J. 1985: State Highway 1 realignment, Ohau Point, Kaikoura. Botanical Report, Botany Division DSIR (unpublished).
Molloy, B.P.J. 1987: In Connor, H.E.; Edgar, E.: Name changes in the indigenous New Zealand Flora, 1960–86 and Nomina Nova IV, 1983–1986. New Zealand Journal of Botany 25: 115–170.
Molloy, B.P.J. 1989: Punchbowl Corner realignment, State Highway, Kaikoura; Botanical Report.
Botany Division DSIR Vegetation Report No. 676.
Molloy, B.P.J. 1994: State Highway 1 – Resource Consents: Vegetation Survey. Landcare Research Contract Report LC9495/45 (unpublished).
Molloy, B. 2001: Pachystegia rufa and allied rock daisies. Conservation Advisory Science Notes No.
336. Wellington, Department of Conservation.
Molloy, B.P.J.; Simpson, M.J.A. 1980: Taxonomy, distribution and ecology of Pachystegia (Compositae): A progress report. New Zealand Journal of Ecology 3: 1–3 Simpson, M.J.A.; Molloy B.P.J. 1978: Seed set and germination in Pachystegia. Canterbury Botanical Society Journal 12: 9–13.
Other unpublished material consulted:
Bartlett, R. 1996: Vegetation in the vicinity of the proposed quarry site, Little Haldon Hills.
Unpublished report prepared for Tranz Rail New Zealand Limited by Kingett Mitchell & Associates.
Molloy, J. et al. 2000: Classifying species according to the threat of extinction. Draft for comment May 2000. Biodiversity Recovery Unit, Wellington, Department of Conservation.
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