Metrosideros: iron heart
kermadecensis: From the Kermadec Islands
Current Threat Status
2018 - Threatened - Nationally Critical
Previous Threat Status
2012 - At Risk - Naturally Uncommon
2009 - At Risk - Naturally Uncommon
2004 - Range Restricted
2012 - IE, OL
2009 - IE, OL
Metrosideros kermadecensis W.R.B.Oliv.
Tree bearing leathery elliptical leaves that are white underneath and bearing scattered red bristly flowers inhabiting the Kermadec Islands (and planted in New Zealand). Leaves 2-5cm long, widest at the middle. Flowers composed from many red filaments around a green glossy disk that is fuzzy white underneath.
Vascular - Native
Metrosideros polymorpha Hook.f. and Metrosideros villosa Kirk are heterotypic synonyms of M. polymorpha Gaudich., Metrosideros villosa Sm.
Endemic. Kermadec Islands: Raoul, North and South Meyer Islands, Herald Isltes (Napier, Nugent and Dayrell)
The dominant canopy tree on Raoul Island where it is found from the coastline to the highest peaks. Forms the main tree of both dry and wet forest types. It was supposedly also present on Macauley Island although there are no herbarium specimens known to substantiate this claim.
Multitrunked (rarely single) tree up to 20 m tall usually with a broadly spreading, domed canopy; trunk up to 3 m diameter, if more than one usually much smaller; trunk surface often covered in adventitious roots. Bark mostly firm, tessellated to platy, grey, grey-brown or whitish, often covered in sparse to dense growths of lichens, liverworts and mosses. Branches erect to spreading, sometimes scrambling across forest floor in which case often rooting freely where touching the ground. Branchlets terete, numerous toward branch ends. Young branchlets, leaf undersides, inflorescence-axes, hypanthia, and sepals densely clad in tomentum, tomentum initially white, maturing dirty grey. Petioles 5-7 mm long, terete to subterete, very coriaceous; lamina 20-50 × 10-30 mm, dull dark green above with appressed, greyish indumentum along the midrib, sometimes extending along the upper surface of the base of the leaf, orbicular, suborbicular, broadly ovate- to elliptic-oblong, apex obtuse to retuse, base obtuse to cuneately-narrowed, coriaceous, margins weakly to strongly recurved. Inflorescence complex, comprising 2 or more terminal compound corymbiform cymes each bearing numerous flowers; pedicels rigidly stout, 8-12 mm long. Hypanthium obconic to turbinate, sepals coriaceous to subcoriaceous, deltoid to triangular, gland-tipped; petals caducous, fleshy, scarlet, crimson to pink, 2.2-3.2 × 2.0-3.0, orbicular, suborbicular to oblong, glabrescent. Stamens numerous, filaments crimson, 10-23 mm long; anthers versatile, yellow, 1.0 × 0.2-0.4 mm. Nectarial disc initially green at anthesis, maturing red or red-green. Ovary 3-locular, adnate to hypanthium; capsules long-persistent, woody, 3-valved, 6.0-7.2 mm long, receptacle distinctly exserted, outer surface and inner sepals and hypanthial rim covered in appressed white to greyish-white tomentum. Seeds numerous, 2.5-4.5 mm long, yellow to pale orange, very narrowly elliptic to linear, 2-4-angled, body often twisted, laterally compressed, apex curved or hooked.
Metrosideros kermadecensis is the only species of that genus found on the Kermadec Islands so in the wild it is not likely to be confused with any other plant. In New Zealand it is commonly cultivated and sometimes sold as pohutukawa (Metrosideros excelsa). From that species it differs by its smaller (20-50 × 10-30 mm cf. 25-100 × 25-35 mm in M. excelsa), orbicular, suborbicular, broadly ovate- to elliptic-oblong (rather than elliptic to oblong, broadly-lanceolate, acute or obtuse) leaves. However, populations of M. excelsa on the Three Kings Islands approach M. kermadecensis in having smaller more consistently elliptic-oblong leaves. In cultivation Metrosideros kermadecensis seems to have no set flowering period with flowers seen throughout the year.
Throughout the year
Main Flower Colour
Red / Pink
Other Flower Colour
Throughout the year
Easy from fresh seed. Cuttings can be grown from water shoots. Hybridises with pohutukawa (Metrosideros excelsa). Although cold sensitive it can be grown in most places provided there is adequate shelter. This species frequently has some flowers present throughout the year but it rarely has a major flowering event.
Not Threatened. It is listed as Range Restricted because it is an island endemic which globally occupies such a small area. This is the dominant tree on Raoul Island and it is also prominent on the nearby Meyer Islands and Napier, Dayrell and Nugent in the Herald Islets.
2n = 22
Where To Buy
Commonly sold in most garden centres in New Zealand, often - unfortunately - mislabelled as Metrosideros excelsa.
References and further reading
Allan, H.H. 1961: Flora of New Zealand. Vol. I, Government Printer, Wellington
This page last updated on 6 Dec 2014