Species

Olearia gardneri

Etymology

Olearia: Derived from the latinised name (Olearius) of the 17th century German botanist Adam Oelenschlager
gardneri: Commemorating the New Zealand botanist Rhys O. Gardner (1949-)

Common Name(s)

Gardner's tree daisy

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 - CD, RF
2009 - CD, RF

Authority

Olearia gardneri Heads

Family

Asteraceae

Brief Description

Rare small-leaved shrub with wide-angled flattened reddish stems bearing clusters of thin leaves inhabiting river valleys of the southern North Island. Leaves 10-15mm long by 7-10mm wide, oval. Flowers small, white, in small groups at base of leaves. Seeds fuzzy.

Flora Category

Vascular - Native

Structural Class

Dicotyledonous Trees & Shrubs

Synonyms

None

Distribution

Endemic. North Island. Formerly known from the Hawkes Bay, southern Central North Island (near Taihape) and Wairarapa. Now only known from the vicinity of Mataroa near Taihape and from widely scattered sites in the eastern Wairarapa

Habitat

The exact habitat preferences of this species are unclear. The majority of plants have been gathered from Matai/Totara/Kahikatea forest remnants on alluvial terraces, developed on calcareous siltstones. In these habitats O. gardneri is associated with the dense shrub tier dominated by numerous divaricating shrubs and trees, which is common to this forest type in the drier eastern North Island. Plants often grow adjacent semi-permanent water pools or in sites flooded in winter.

Features

Deciduous shrub or small tree up to 3 m tall; stems often layering. Bark greyish–white, rough, grooved. Branchlets with 2 flanges, slender, dark reddish brown. Leaves of seedlings broadly deltoid, margins with 3–4 prominent teeth. Leaves of adults opposite or in fascicles of 2–4 on brachyblasts, spathulate, petioles 5–10 mm long mm; lamina 10–35 × 7–17 mm, broadly ovate-elliptic, light green above, more or less glabrous below with a few scattered long and silky hairs but no tomentum, margin entire, apex obtuse and apiculate. Inflorescence solitary or in fascicles of 2–6 capitula on brachyblasts, capitula c. 5 × 4 mm, peduncles 6–10 mm long. Involucral bracts c. 16, obovate, glabrous, membranous, purple tinged, apex acute. Florets 10–19, white. Ray florets c. 9, 5 mm long, limb c. 1 mm long. Disc florets c. 10, 6 mm long, lower half of corolla tube with very short, rather glandular hairs. Achenes 1–2 mm long, narrow–obovate, with short patent or slightly antrorse hairs; pappus hairs 2–3 mm long.

Similar Taxa

Olearia gardneri is allied to the South Island O. hectorii Hook.f. From that species it differs by the broadly deltoid, truncate, rather than oblanceolate juvenile leaves, by the smaller, distinctly less hairy adult leaves, white rather than yellow flowers, and narrowly lanceolate, toothed, finely hairy phyllaries (bracts surrounding the flowers). The phyllary hairs are long and wavy.

Flowering

October - December

Flower Colours

White

Fruiting

February - April

Propagation Technique

Can be grown from fresh seed when available. Hardwood cuttings will strike if taken after leaf fall and placed within a cold frame.

Threats

Approx 110 adult specimens left in the wild. The majority occur on unprotected land next to a reserve near Taihape. Most other sites are single plants, often in ill-thrift and/or growing in severely deteriorated habitats. This species remains acutely threatened through recruitment failure (the seed cannot germinate through the dense grass swards which now surround most trees), the ill-thrift and presumed old-age of many of the surviving trees. Indications are that seed produced by many trees has very low viability, and there are concerns that the species may have a high level of self-incompatibility. This will seriously impact on current management practices which involve harvesting seed from the wild, germinating plants, and planting these back directly under their parent tree(s).

Chromosome No.

2n = 108

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

Note

Numerous specimens grow in the grounds of the Masterton Area Office, Wellington Conservancy, New Zealand Department of Conservation, and at Mt Bruce National Wildlfie Centre.

Attribution

Fact Sheet prepared for NZPCN by P.J. de Lange 1 July 2007. Description by P.B. Heenan and P.J. de Lange subsequently published in de Lange et al. (2010)

References and further reading

de Lange, P.J.; Heenan, P.B.; Norton, D.A.; Rolfe, J.R.; Sawyer, J.W.D. 2010: Threatened Plants of New Zealand. Canterbury University Press, Christchurch.

Heads, M. 1998. Biodiversity in the New Zealand divaricating tree daisies: Olearia sect. nov. (Compositae). Botanical Journal of the Linnean Society 127(3): 239-285.

This page last updated on 19 Dec 2014