Pouzolzia australis
Common names
Kermadec nettle-tree
Biostatus
Native
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2023 | Threatened – Nationally Endangered | Qualifiers: RR, TO
Category
Vascular
Structural class
Trees & Shrubs - Dicotyledons
Simplified description
Small bushy tree bearing light green soft wrinkled triangular pointed leaves that have prominent veins on the whiteish underside inhabiting Raoul Island in the Kermadec Islands. Wood soft. Leaves 7–15 cm long, edge with evenly spaced teeth. Flowers tiny, in small round clusters at base of leaves.
Flower colours
Brown, White
Detailed description
Shrub or small tree up to 8 m tall. Branchlets at first covered in fine white pubescence, maturing with age grey. Leaves alternate, 60–200 × 30–60 mm, ovate-ovate-lanceolate, borne on stout petioles 25–30 mm long, leaf apex acuminate, upper surface glabrescent, rugulose to almost smooth, undersides finely clad in dense white hairs (so giving a white colour to leaf undersides). Midrib and veins prominent, glabrescent, yellow-green. Inflorescences numerous, sessile, axillary glomerules (clusters). Male flowers with acuminate perianth segments 2–3 mm long, clad in stiff hairs. Female flowers with tubular perianth up to 2 mm long, contracted at 2-toothed apex; stigma filiform, protruding. Fruits compressed, broadly winged, the ovoid achenes minute.
Similar taxa
None within the New Zealand Botanical Region (for a definition of this area see Allan 1961). Wilmot-Dear & Friis (2006) transferred Boehemeria australis to Pouzolzia and in the process reduced the Lord Howe endemic B. calophleba and Kermadec Islands endemic B. australis subsp. dealbata into P. australis. While their conclusion about the Lord Howe species needs further investigation (the Lord Howe plant is very different from the Norfolk and Kermadec Island plants), their decision about Kermadec and Norfolk plants seems justified. Previously the Kermadec plant had been distinguished from the Norfolk Island nettle tree by its having somewhat whiter undersides to the leaves, and by its slightly less rugose upper leaf surface (see Sykes in de Lange et al. 2005). These distinctions seem relatively minor and without further investigation using modern molecular tools it does seem that the more detailed morphological analysis by Wilmot-Dear & Friis (2006) should be followed.
Distribution
As currently circumscribed by Wilmot-Dear & Friis (2006) Pouzolzia australis is indigenous to Norfolk and Lord Howe Islands as well as the Kermadec Islands, where it is now known only from Raoul and Macauley Islands. While the merger of Boehmeria australis subsp. dealbata with B. australis subsp. australis into Pouzolzia as P. australis seems sensible, the merger of the very distinctive Lord Howe endemic Boehmeria calophleba requires further critical study before it should be universally followed. For a concise explanation of the differences between Boehmeria and Pouzolzia see Wilmot-Dear et al. (2009).
Habitat
Coastal forest, cliff faces, recent and semi-stable slips, low scrub.
Threats
Formerly threatened with extinction through heavy browsing pressure from goats. Following the eradication of goats from Raoul Island Kermadec nettle tree did not at first recover. Indeed it seems to have declined further and for a decade or so it became very scarce. It was presumed that this was caused by competition from weed species, which had, following the goat eradication, rapidly spread into the type of habitat it was assumed Kermadec nettle tree requires. Current fieldwork now suggests that Kermadec nettle tree on Raoul Island remains a very localised species of the open ridgeline forest, slip scars and valley heads where it seems to remain in small b ut stable populations. In May 2011 Pouzolzia was rediscovered on Macauley Island where it had been believed to have gone extinct over a 100 years before. Visited to that island in 2017 and 2018 did not look for the species, so its status there remains unknown. The species is seriously threatened on Norfolk Island.
Detailed taxonomy
Genus
Family
Synonyms
Boehmeria dealbata Cheeseman, Boehmeria australis var. dealbata (Cheeseman) Sykes, Boehmeria australis subsp. dealbata (Cheeseman) Sykes, Boehmeria calophleba C.Moore et F.Muell
Endemic taxon
No
Endemic genus
No
Endemic family
No
Ecology
Flowering
Year round
Fruiting
Year round
Propagation technique
Very easily grown from fresh seed and cuttings. Plants often arise spontaneously in cultivation from the abundant viable seed produced by established specimens. Very cold sensitive.
Other information
Cultivation
Sold by several specialist native plant nurseries.
Plant of the Month
This plant has been featured as a Plant of the Month – see Trilepidea: NZPCN newsletter for July 2005 for the full story.
Etymology
australis: Southern
NVS code
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
POUAUS
Chromosome number
2n = 28
Previous conservation statuses
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2017 | Threatened – Nationally Endangered | Qualifiers: RR, St, TO
2012 | At Risk – Naturally Uncommon | Qualifiers: EF, RR, TO
2009 | At Risk – Naturally Uncommon | Qualifiers: OL, IE
2004 | Threatened – Nationally Endangered
Referencing and citations
References and further reading
Allan HH. 1961. Flora of New Zealand, Volume I. Indigenous Tracheophyta: Psilopsida, Lycopsida, Filicopsida, Gymnospermae, Dicotyledones. Government Printer, Wellington, NZ. 1085 p.
de Lange PJ, Gardner RO, Sykes WR, Crowcroft GM, Cameron EK, Stalker F, Christian ML, Braggins JE. 2005. Vascular flora of Norfolk Island: some additions and taxonomic notes. New Zealand Journal of Botany 43(2): 563–596. https://doi.org/10.1080/0028825X.2005.9512975.
Wilmot-Dear CM, Friss I. 2006. The Old World species of Pouzolzia (Urticaceae, tribus Boehmerieae). A taxonomic revision. Opera Botanica (Nordic Journal of Botany) 24: 5–114. https://doi.org/10.1111/j.1756-1051.2004.tb00825.x
Wilmot-Dear CM, Acharya N, Kravtsova TI, Friis I. 2009. Pouzolzia rugulosa transferred from Boehmeria, and the distinction between Boehmeria and Pouzolzia (Urticaceae). Edinburgh Journal of Botany 66: 51–64. https://doi.org/10.1017/S096042860900523X.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange 30 August 2009. Description adapted from Allan (1961).
Some of this factsheet information is derived from Flora of New Zealand Online and is used under a Creative Commons Attribution 3.0 New Zealand licence.
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Pouzolzia australis Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/pouzolzia-australis/ (Date website was queried)