Acaena rorida
Biostatus
Native
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Flower colours
White
Detailed description
Stoloniferous, prostrate, perennial herb, forming dense patches. Prostrate stems c.70–250 mm long, rooting at nodes, erect stems 3–15 × 0.7 mm, brown, sparsely hairy. Leaves imparipinnate, 1–2(–5) × 5–12 mm. Stipules 2–4 mm long, margins and tips hairy, free portion 1 mm long, entire or bifid, acuminate, Leaflets 4–5, reducing in size toward base, suborbicular, 2–7 × 2–5 mm, truncate at apex; upper surface dull, pale olive, apple green or pinkish-purple, glabrous, veins distinct; lower surface paler, subglaucous; veins with appressed hairs; teeth 7–11, brown. Scapes 6–15 mm long at flowering, on short shoots hidden in foliage, densely hairy, scape bract 0 or 1, leaf-like. Capitulum 4–5 mm diam., 10 mm diam (including spines) at fruiting; florets c.10–12; sepals 4, stamens 2; styles 2; both white. Fruit 1.5 × 1.5 mm. Achenes 2, enclosed within turbinate, red-brown, 4-ribbed, hypanthium. Spines 0 or 1, 1–10(–15) mm long, pale red, tapered to naked tip.
Similar taxa
Acaena microphylla Hook.f. is rather similar. This species has rich-green to greenish brown mottled foliage with shining cuticles, and scapes up to 250 mm long, which hold the capitula well above the foliage. As far as is known A. microphylla is not present in the North West Ruahine area.
Distribution
Endemic. North Island. North West Ruahine Range, where it is only known from ravines draining the Mangaohane Plateau and from the nearby Makirikiri Tarns.
Habitat
Damp hollows within tussock grassland, and associated limestone ravines.
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.
Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – these interim threat classification statuses has not been assessed by the NZTCS panel.
- 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 Critical | Qualifiers: DPT, OL
Threats
Weed invasion by Pilosella spp., Agrostis spp. and hybridisation with Acaena anserinifolia.
Detailed taxonomy
Family
Rosaceae
Synonyms
Acaena microphylla var. microphylla Hook.f.
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
Although exact flowering times are not known, plants have been seen in flower in April.
Fruiting
Although exact fruiting times are unknown plants have been seen in fruit in April.
Propagation technique
Easily grown by division. This species rarely flowers in cultivation (at least within the North Island—although it has been reported that the species flowers each year in Dunedin) and it would seem that no one has yet tried to germinate seed.
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]
FAC: Facultative
Commonly occurs as either a hydrophyte or non-hydrophyte (non-wetlands).
Other information
Plant of the Month
This plant has been featured as a Plant of the Month – see Trilepidea: NZPCN newsletter for February 2011 for the full story.
Etymology
acaena: From the Greek ‘akanthos’ thorn, referring to the spiny calyx that many species have
rorida: From the Latin meaning dewy, wet with dew
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.
ACAROR
Chromosome number
2n = 42
Previous conservation statuses
2017 | Threatened – Nationally Critical | Qualifiers: OL
2012 | Threatened – Nationally Critical | Qualifiers: OL
2009 | Threatened – Nationally Critical | Qualifiers: OL
2004 | Threatened – Nationally Critical
Referencing and citations
References and further reading
Macmillan, B.H. 1991: Acaena rorida and Acaena tesca (Rosaceae) — two new species from New Zealand. New Zealand Journal of Botany 29: 131–138
Thorsen, M. J.; Dickinson, K. J. M.; Seddon, P. J. 2009: Seed dispersal systems in the New Zealand flora. Perspectives in Plant Ecology, Evolution and Systematics 11(4): 285–309.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange 1 October 2003. Description adapted from MacMillan (1991).
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Acaena rorida Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/acaena-rorida/ (Date website was queried)