The New Zealand Plant Conservation Network

Species

Acaena rorida

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

Common Name(s)

none known

Current Conservation Status

2012 - Threatened - Nationally Critical

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 - Threatened - Nationally Critical
2004 - Threatened - Nationally Critical

Qualifiers

2012 - OL
2009 - OL

Authority

Acaena rorida B.H.Macmill.

Family

Rosaceae

Flora Category

Vascular - Native

NVS Species Code

ACAROR

Structural Class

Dicotyledonous Herbs other than Composites

Synonyms

Acaena microphylla var. microphylla Hook. f.

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.

Features

Stoloniferous, prostrate, perennial herb, forming dense patches. Prostrate stems c.70-250 mm long, rooting at nodes, erect stems 3-15 x 0.7 mm, brown, sparsely hairy. Leaves imparipinnate, 1-2(-5) x 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 x 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 x 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.

Flowering

Although exact flowering times are not known, plants have been seen in flower in April.

Flower Colours

White

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.

Threats

Weed invasion by Pilosella spp., Agrostis spp. and hybridisation with Acaena anserinifolia.

Chromosome No.

2n = 42

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

 

 

  

Attribution

Fact sheet prepared for NZPCN by P.J. de Lange 1 October 2003. Description adapted from MacMillan (1991).

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 2009 Vol. 11 No. 4 pp. 285-309

This page last updated on 19 Dec 2014