Acaena juvenca
Common names
bidibid, piripiri
Biostatus
Native – Endemic taxon
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 | Not Threatened
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Simplified description
An evergreen mildly hairy green herb, which spreads up to a 1 metre across and up to 10 cm in height. The pinnate leaves are delicate and sharp toothed and may have a pinkish or light brown contrasting coloured margin. The globe shaped flower balls are white and pale green and grow into a cluster of hooked spikes, which when ripe brown off, become firm and may stick to your socks or laces when brushed past in order to disperse.
Flower colours
White
Detailed description
Stoloniferous, prostrate, trailing perennial herb, forming a loose mat up to 1 metre in diameter. Stems less than 1.5 mm diameter, sparsely to densely covered with bristle-like hairs, up to 30 cm long, and/or 10 cm high; Stipules entire or bifid, deeply incised; Leaves odd-pinnate, between 17-50 mm long with 3-11 leaflets; Leaflets profoundly reduced below 3(-5) distal obovate-orbicular leaflets, serrated toothed margin, teeth sharp often light-brown or pale pink, 8-14 hair-tipped teeth per leaflet, upper surface flat vivid green veins obvious, lower surface pale green hair covered; Inflorescence scape 40-150 mm, pale brown stem rather hairy; Capitulum of 45-60 florets, each floret has 4 sepals, 2 stamen, white anthers, 1 white style, 1 achene; Fruit roughly cone-shaped, each having 4 barb-tipped spines, up to 4-6 mm long, mature dry, pale brown when ripe, enabling attachment to passing hairy/feathered surfaces as vector.
Similar taxa
Acaena anserinifolia, is a similar colour and could be mistaken, however the stipules are generally more divided 3-8-fid, rather entire or bifid as in A. juvenca. A. anserinifolia leaflet veins are indistinct on upper surface of leaflets and have more leaflet pairs present 4-6 rather than 3-5 in A. juvenca.
Acaena emittens is a very similar plant, with just a few differences, the leaflets have shallow rounded teeth compared to the sharp teeth of A. juvenca. A. emittens leaflet veins are indistinct on upper surface of leaflets.
Distribution
Endemic. North Island: southern Kaimanawa Mountains, Rangitikei, Hautapu, and Moawhango Valleys, northern Ruahine Range, inland Hawke’s Bay, Wairarapa district, and Pukerua Bay; South Island: Nelson, Marlborough, east of the main divide in Canterbury, Otago, and Southland; Stewart Island/Rakiura
Habitat
Coastal to montane (0-1200 m.a.s.l.), open forest, forest margins, shrublands and grasslands.
Detailed taxonomy
Genus
Family
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
(October-)November-February
Fruiting
January-April
Life cycle and dispersal
Spiny hypanthia are dispersed by attaching to fur, feathers and clothing and possibly also dispersed by wind and granivory (Thorsen et al., 2009)
Other information
Etymology
acaena: From the Greek ‘akanthos’ thorn, referring to the spiny calyx that many species have
juvenca: From the Latin word ‘iuvenca’ meaning young cow or heifer, which refers to the appearance of the mature form of this plant resembling the juvenile form of its close relative A. anserinifolia.
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.
ACAJUV
Chromosome number
2n = 42
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 | Not Threatened
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Regional conservation statuses
Otago: 2025 | Regionally Not Threatened | Qualifiers: TL
The regional threat classification system leverages off the national assessments in the NZTCS, providing information relevant for the regional context. Otago conservation status information is sourced from the “Conservation Status of Indigenous Vascular Plants in Otago, 2025” Jarvie S et al. (2025) report.
Referencing and citations
References and further reading
Lloyd K. 2001. A Key and notes for Acaena (Rosaceae) in New Zealand. Botanical Society of Otago Newsletter 25. Pgs.10-14.
Macmillan BH. 1989. Acaena juvenca and Acaena emittens (Rosaceae) — two new species from New Zealand. New Zealand Journal of Botany 27(1): 109-117. DOI:10.1080/0028825X.1989.10410149
Thorsen MJ, Dickinson KJM, Seddon PJ. 2009. Seed dispersal systems in the New Zealand flora. Perspectives in Plant Ecology, Evolution and Systematics 11: 285–309. https://doi.org/10.1016/j.ppees.2009.06.001.
Attribution
Fact sheet prepared for NZPCN by MD Ward (August 28th 2025) Description adapted from Lloyd (2001), NZ Flora (2025).
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.