Acaena emittens


Acaena: From the Greek 'akanthos' thorn, referring to the spiny calyx that many species have

Common Name(s)

Bidibid, piripiri

Current Conservation Status

2012 - At Risk - Naturally Uncommon

Conservation status of New Zealand indigenous vascular plants, 2012
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2012 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2009 and replaces all previous NZTCS lists for vascular plants. Authors: Peter J. de Lange, Jeremy R. Rolfe, Paul D. Champion, Shannel P. Courtney, Peter B. Heenan, John W. Barkla, Ewen K. Cameron, David A. Norton and Rodney A. Hitchmough. File size: 792KB

Previous Conservation Status

2009 - At Risk - Naturally Uncommon
2004 - Not Threatened


2012 - Sp


Acaena emittens B.H.Macmill.



Flora Category

Vascular - Native

NVS Species 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.

Structural Class

Dicotyledonous Herbs other than Composites


None (described in 1989)


Endemic. New Zealand: North Island (eastern Tongariro National Park, southern Kaimanawa Mountains, Kaweka Range, Taruarau River, Otupae Range, north-west Ruahine Range)


A species of relatively open montane Nothofagus forest and scrub especially that dominated by kahikatoa (Leptospermum scoparium J.R.Forst. et G.Forst.), and in open disturbed sites near the bush line.


Slender suffruticose perennial with dark brown subterranean stems < 2 mm diam. Branches prostrate and < 500 mm long or erect and < 50 mm long, c.0.7 mm diameter, brown, hirsute, epidermis flaking with age; internodes < 35 mm long on prostrate stems. Leaves hairy; stipules 2-6 mm long, margins, tips and undersides hairy, free portion linear, entire or bifid, < sheath; leaflets 3 or 4 pairs, the distal leaflet and 2 upper pairs obovate to suborbicular in outline, truncate at apex, shallowly cuneate at base, 2-10 × 2-6 mm; upper surface dull green, glabrous, smooth, with secondary venation indistinct; lower surface pale, glaucescent, the veins with appressed hairs; teeth 7-9 with margins thickened and recurved, hydathodes pink. Basal leaflet pairs less than ½ the size of the penultimate pair, or linear and smaller than stipule lobes. Hairs simple, unicellular, < 1.5 mm long, on stipules, rachis and leaflets. Scapes terminal on short shoots, 40-130 mm long at flowering, hardly elongating as fruit matures, c.0.5 mm diameter, moderately hairy, pale brown. Scape bract linear or foliose, occasionally subtending a single floret. Capitulum 4-6 mm diameter at flowering, 10-15 mm diameter (including spines) at fruiting. Bracteoles on receptacle linear, c. 3 mm long, with hairy margins. Florets c. 40-50, minutely stipitate. Hypanthium c.1 mm long, enclosing perigynous ovary, densely hairy, bearing 4 barbed spines which reach above the hypanthium rim. Sepals 4, arising from hypanthium rim, shortly joined at base, c. 1.5 mm long, elliptic, narrowed and thickened at tip, sparsely hairy on underside. Petals 0. Stamens 2; filaments unequal, up to 2 mm long; anthers 0.3 x 0.5 mm, white. Style 1, 1.5 mm long, including white, fimbriate stigma 0.6 mm broad and protruding from aperture of hypanthium. Fruit indehiscent with a single achene enclosed in the hypanthium, obconic, c.2.0 × 1.2 mm, brown, moderately hairy, 4-ribbed; spines 1 per rib, slender, 4-6 mm long, pale rose or brown, bearing a single rank of translucent, retrorse barbs at tip.

Similar Taxa

Allied to A. anserinifolia (J.R.Forst. et G.Forst.) J.B.Armstr. from which it differs by the leaves < 50 mm long, spathulate; leaflet pairs 3-4, these abruptly reduced in size below the 2 uppermost; leaflet lamina obovate to suborbicular with the teeth, crenate, glossy, 3-5 per side; hairs appressed, absent from upper surface, predominantly on midrib and main veins of lower surface; by the veins indistinct on the upper leaflet surface; by the linear, entire, rarely bifid stipules; by the smaller capitula 4-6 mm diameter at flowering 10-15 mm diameter at fruiting; and small fruits (c.2.0 × 1.5 mm) and spines (4-6 mm long).


December – February

Flower Colours



January – May

Propagation Technique

Easily grown from fresh seed and from rooted pieces.


A Naturally Uncommon endemic of the Central North Island. Although it is not known to be threatened it is not generally that common either

Chromosome No.

2n = 42

Endemic Taxon


Endemic Genus


Endemic Family


Where To Buy

Not Commercially Available


Description from Macmillan (1989).

References and further reading

Macmillan, B.H. 1989: Acaena juvenca and Acaena emittens (Rosaceae) - two new species from New Zealand. New Zealand Journal of Botany 27: 109-117.

This page last updated on 22 Aug 2013