Species

Myoporum semotum

Etymology

Myoporum: shut pore
semotum: m the Latin word for remote or distant

Current Conservation Status

2018 - At Risk - Declining

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

2012 - Threatened - Nationally Vulnerable
2009 - Threatened - Nationally Vulnerable

Qualifiers

2012 - CD, DP, IE, RR

Authority

Myoporum semotum Heenan et de Lange

Family

Scrophulariaceae

Brief Description

Spreading tree bearing glossy leathery oval leaves with small teeth on the edge inhabiting the Chatham Islands. New growth very glossy, green. Flowers white with purple spots, at base of leaves.

Flora Category

Vascular - Native

Structural Class

Dicotyledonous Trees & Shrubs

Synonyms

None

Distribution

Endemic. Chatham Islands: Rangiauria (Pitt Island), Mangere, Little Mangere, Rabbit and Rangatira (South-East) Islands.

Habitat

Coastal forest and scrub where it is often the dominant canopy species.

Features

Tree up to 14m tall, trunk up to to 0.50m dbh, bark smooth to lightly furrowed and pale brown to cream-brown. Branchlets prominently angled, smooth and usually lacking tubercules, but occasionally weakly tuberculate, glabrous, non-resinous, leaf scars raised. Leaf bud and emerging leaves usually black, resinous. Leaves 70-100 × 25-35 mm, ovate, broadly elliptic, oblong-broadly elliptic to occasionally elliptic, glabrous, discolorous, alternate, coriaceous; secretory cavities obscure, minute, immersed in lamina; base cuneate; margins finely serrate distally, sometimes entire; apex acute to sometimes subacute; abaxial surface with midrib prominently raised.Flowers 17.0-18.5mm in diameter, 1-5 per axil, variable number on same branch; pedicels terete, 3-12mm long, glabrous. Sepals 5, 1.3-3.0 × 0.7-1.0mm, narrowly triangular, attenuate, glabrous, apex acute. Corolla bud pale white, open flower white, pink-brown or purple to lavender-purple spotted on lobes and in tube; lobes 4.5-6.5 × 4.0-4.5 mm long, 3.5-5.5 mm across; outer surface of lobes and tube glabrous; inner surface of lobes and tube furnished with succulent hairs; tube hairs c.0.15 mm long, lobe hairs up to 1.0 mm. Stamens 4; filaments 5.0-5.5 mm long, glabrous, tapered toward apex, exserted, inserted about one-third from base from base of corolla tube; anthers 0.9-1.3 × 0.7-0.9 mm,green, glabrous, ovoid, 3-5-locular with one ovule per locule; style 2.8-4.0mm long, white, with pilose patent hairs toward base. Fruit a drupe; exocarp white when immature, becoming purple when mature, drying brown; endocarp 5.0-9.0 × 4.0-5.5 mm, woody, hard, broadly elliptic, elliptic-oblong to ovoid, not compressed, prominently 3-5 angled, apex acute to apiculate, base obtuse; seed 2.8-3.0 × 0.9-1.1 mm, oblong, pale orange-yellow. Description from Heenan & de Lange (2011).

Similar Taxa

Chatham Islands Myoporum is distinguished from ngaio (Myoporum laetum) by the branchlets, petioles and leaf midribs that are usually smooth and lack prominent protruding tubercules, leaves that are broader and thicker, with margins often less serrate, and with secretory cavities that are more dense and less conspicuous as they are more deeply immersed in the mesophyll. It differs from the Kermadec ngaio (Myoporum rapense subsp. kermadecense by leaf, flower and fruit characters (see Sykes 1987; Chinnock 2007). The leaves of both species have obscure pellucid glands, but the leaves of M. rapense subsp. kermadecense are glandular-punctate and usually narrow-elliptic to elliptic-lanceolate, prominently serrated in the distal half to three-quarters and with the apex short to long acumninate. The leaves of the Chatham Islands Myoporum have a smooth surface (not glandular-punctate), are broader with the marginal teeth smaller and confined to the distal one-third of the leaf or with the leaves entire and the leaf apex is acute to subacute. The flowers of M. rapense subsp. kermadecense are 11-15mm diameter and the style is usually hairy to near the apex, whereas the flowers of the Chatham Islands Myoporum are 17.0-18.5mm in diameter and the style hairy at the base. The fruit of M. rapense subsp. kermadecense are smooth or slightly 3-angled and the seeds 2.2-2.7mmlong, whereas the fruit of the Chatham Islands Myoporum are prominently 3-5-angled and the seeds 2.8-3.0mm long.

Flowering

November - February

Fruiting

May

Propagation Technique

As with Ngaio, the Chatham Islands Myoporum is easily grown from fresh seed and hardwood cuttings. Like ngaio too it is very fast growing, and tolerant of wind, salt burn and at least some drought. Plants are cold-sensitive.

Threats

Threatened by unrestricted stock access and pig damage. The species is secure - though very uncommon - on Rangatira and Little Mangere, and is being actively replanted as part of the forest restoration process on Mangere Island. One shrub is known from Rabbit Island. Where stock and pig access is restricted recruitment is evident with most size classes present. These observations suggest that with simple management, i.e. fencing and excluding browsing animals Myoporum populations should recover quickly. Currently there seems to be no ngaio present on Rangiauria, as it is very likely that it will hybridise with the Chatham Islands Myoporum it is important to ensure that ngaio is not planted on that island.

Chromosome No.

2n = 108

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

Attribution

Fact Sheet prepared for the NZPCN by: P.J. de Lange (22 April 2011). Description from Heenan & de Lange (2011).

References and further reading

Chinnock, R.J. 2007: 2007. Eremophila and allied genera: a  monograph of the plant family Myoporaceae. Kenthurst, Australia, Rosenberg.

Heenan, P.B.; de Lange, P.J. 2011: Myoporum semotum (Scrophulariaceae), a new tree species from the Chatham Islands. New Zealand Journal of Botany 49: 17-26.

Sykes WR 1987. Kermadec ngaio (Myoporum, Myoporaceae). New Zealand Journal of Botany 25: 595-601.

This page last updated on 15 Mar 2015