Species

Metrosideros bartlettii

Etymology

Metrosideros: iron heart

Common Name(s)

rata moehau, Bartlett's rata

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, RR
2009 - CD, RR

Authority

Metrosideros bartlettii J.W.Dawson

Family

Myrtaceae

Brief Description

Forest tree (up to 30 m tall). Bark grey-white to white, spongy, tissue-like, and readily flaking. Emergent leaves yellow-green, mature leaves dark green, margins distinctly hairy. Inflorescences white.

Flora Category

Vascular - Native

NVS Species Code

METBAR

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

Synonyms

None

Distribution

Endemic. North Island, Northland, Te Paki, where it is only known from three forest remnants near Spirits Bay. These are Radar Bush, Kohuronaki and Unuwhao Bush.

Habitat

An emergent or canopy tree of northern coastal and lowland broad-leaved forest. Usually starting life as an epiphyte on puriri (Vitex lucens), taraire (Beilschimedia tarairi ), rewarewa (Knightia excelsa) and tree ferns (Cyathea spp.). Occasional specimens have been found growing terrestrially on rock outcrops, boulders and cliff faces.

Features

Tree up to 30 m with a trunk up to 1.5 m diameter, often initially epiphytic on trees or tree ferns; bark pale grey to whitish, spongy, separating into soft flakes, shedding freely; young twigs dark red, 4-angled to rounded and with long-persistent, white spreading hairs. Leaves on petioles 4–5 × 1 mm, lamina 30–50 × 15-26 mm, elliptic to ovate, base cuneate, apex acute to attenuate, often twisted; young leaves pale green to yellow-green, somewhat glossy, petioles, margins and midribs pubescent, with the hairs tending to persist on midribs and petioles; mature leaves dark green above pale beneath, upper surface glossy, veins evident, lower surface glossy, entire vein network evident, oil glands obscure, midrib raised below, impressed above. Inflorescences with 3-4 pairs of cymules, ± densely tomentose, tomentum of spreading white hairs; bracts and bracteoles shedding early during inflorescence maturation; peduncles up to 9 × 1 mm. Flowers white; pedicels up to 3 × 1 mm; hypanthium 2.5-3.0 ×2.0-2.5 mm; sepals triangular, spreading, 1.0–1.5 × 1.0–1.5 mm; petals elliptic to ovate, 2.5-–3.0 × 1.8–.0 mm; stamens 5–9 mm long; style 10–11 mm long. Fruit hypanthium puberulent, 2.0–2.5 × 2.5–3.0 mm, sepals persistent, deflexed, capsules exserted for 1.5-2.5 mm. Seeds pale orange-yellow, 2.3-3.0 mm long, narrowly elliptic to narrowly oblong, straight or slightly curved.

Similar Taxa

Bartlett's rata could only be confused with northern rata (Metrosideros robusta) from which it can immediately be distinguished by the acute tipped rather than notched leaves. The flowers of northern rata are red or yellow, never white, and the capsule valves of that species never protrude beyond the calyx rim. No other New Zealand Metrosideros has such easily detached, white, tissue-paper-like bark.

Flowering

October - November

Flower Colours

White

Fruiting

March - April

Propagation Technique

Easily grown from fresh seed. Can also be grown by hardwood cuttings but these can be slow to take root. Plants have proved tolerant of a wide range of conditions, and have survived mild frosts and even snow falls. However specimens do best in open, sunny sites within well drained, fertile soils.

Threats

There are now only 25 adult Bartlett's rata left in the wild (down from the 34 known in 1992), mostly on private land and isolated from other specimens. There is negligible viable seed set because there is not an abundance of nectar-feeding birds to pollinate the flowers and Bartlett's rata is self-incompatible. There is also minimal genetic variation, and most of this occurs on private land. Aside from these problems, the species is at severe risk from browsing animals and fire. Indeed, uncontrolled possums are currently wiping out this tree at the largest population known, which occurs on private land. Bartlett's rata is occasionally cultivated, but most cultivated specimens come from a single tree.

Chromosome No.

2n = 22

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

Where To Buy

The species is occasionally sold by some commericial nurseries.

Attribution

Fact sheet prepared for NZPCN by P.J. de Lange (30 September 2003). Description adapted from Dawson (1985) supplemented with observations made from herbarium and fresh material.

References and further reading

Dawson , J.W. 1985: Metrosideros bartlettii (Myrtaceae) a new species from North Cape, New Zealand. New Zealand Journal of Botany 23: 607–610.

This page last updated on 19 Dec 2014