Species

Olearia semidentata

Etymology

Olearia: Derived from the latinised name (Olearius) of the 17th century German botanist Adam Oelenschlager
semidentata: partially toothed

Common Name(s)

Chatham Island aster, swamp aster, hanga-tare

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 - Range Restricted

Qualifiers

2012 - IE, RR
2009 - IE

Authority

Olearia semidentata Decne.

Family

Asteraceae

Brief Description

Small tree with narrow leathery saw-edged dark green leaves that are white underneath and large pinkish-purple daisy-like heads inhabiting swamps on the Chatham Islands. Leaves 3.5-7cm long by 0.5-1cm wide, widest at middle, with large thick teeth spaced along edge. Flowers 2.5-3.5cm wide.

Flora Category

Vascular - Native

NVS Species Code

OLESEM

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 Trees & Shrubs

Distribution

Endemic. Chatham Islands only

Habitat

A shrub of peaty ground and bogs, swamp aster is usually associated with bamboo rush in peat rush-shrubland. It is a rapid coloniser of burnt bog sites in the absence of cattle.

Features

It is an erect shrub that grows 2–3 m tall. The leaves are narrow and lance-shaped, with widely spaced teeth towards the tip. Both the leaves and the branchlets are covered in soft, white hairs. Flower heads are usually brilliant mauve in colour, but fade to pink with age. These flowers can be seen from November to March. The fruit which ripen from January to June are crowned by hair-like bristles.

Flowering

November - March

Flower Colours

Violet / Purple,White

Fruiting

January - June

Threats

Threatened by repeated burning, accompanied by drying out of the soil and the presence of cattle.

Chromosome No.

2n = 108

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

Where To Buy

Not commercially available.

Attribution

Fact Sheet prepared for NZPCN by P.J. de Lange 1 August 2003.

References and further reading

Walls, G.; Baird, A.; de Lange, P.J.; Sawyer, J.W.D. 2002: Threatened plants of the Chatham Islands. Wellington, Department of Conservation.

This page last updated on 7 May 2014