Lophomyrtus obcordata

Species

Lophomyrtus obcordata

Etymology

Lophomyrtus: From the Greek lophos (crest) and myrtus (myrtle)
obcordata: heart-shaped and notched at the tip

Common Name(s)

Rohutu

Current Threat Status

2018 - Threatened - Nationally Critical

Previous Threat Status

2012 - Not Threatened
2009 - Not Threatened
2004 - Not Threatened

Authority

Lophomyrtus obcordata (Raoul) Burret

Family

Myrtaceae

Brief Description

Bushy shrub with a corded smooth trunk under flakes of bark bearing small thick heart-shaped leaves. Leaves 5-10mm long, with a distinct notch at tip. Flowers white, single, 6mm wide, with many filaments from white glossy centre, on a stalk to 20mm long. Fruit red to black.

Flora Category

Vascular - Native

Synonyms

Eugenia obcordata Raoul, Myrtus obcordata (Raoul) Hook.f.

Distribution

Endemic. North and South Islands. Patchy and often absent over large parts of the country. More common in the eastern North and South island though locally prominent in some parts of western Northland and Auckland.

Habitat

Coastal to montane in forest - though mostly found in coastal and lowland forested habitats. Lophomyrtus obcordata is often rather local over large parts of its range though it seems to be reasonably common on the Pouto and Kaipara Peninsula where it grows on stable sand dunes in a forest dominated by an as yet unnamed species of Kunzea ericoides (known as rawirinui to northern Maori and referred to by de Lange & Murray 2004, de Lange et al., 2005 and de Lange et al. 2010 as Kunzea aff. ericoides (a)). Lophomyrtus obcordata is also occasionally dominant in alluvial forest remnants of the eastern South Island. In these places it is often parasitised by the dwarf mistletoe Korthalsella lindsayi.

Features

Shrub up to c.6 m tall. Trunk slender, up to 02 m diameter. Bark greyish pink, chartaceous, flaking in large, irregular shards, underbark pale cream. Branches numerous, erect, compactly branched to spreading. Branchlets intially 4-angled maturing subterete, rather brittle, minutely pubescent. Leaves opposite (sometimes in fascicles), coriaceous, puberulent when young (hairs patent), becoming glabrous with age, glandular punctate, oil glands colourless, leaf lamina and petioles shortly decurrent with branchlet; petiole 0.7-1.0 mm long, brittle; leaf lamina 5-12 × 5-10 mm, obcordate, cuneately narrowed to base, adaxially dark green to grey-green (sometimes tinged red), paler beneath (sometimes tinged pink). Flowers 4-merous, 6-8 mm diameter, borne in axillary, solitary monads on slender, 10-14(-20) mm long, pubescent pedicels. Hypanthium subturbinate, not extending beyond ovary summit, glandular punctate, oild glands colourless (rarely pink tinged), calyx lobes 4, 1.0-1.8 mm long, persistent, spreading, pubescent, oblong, acute. Petals 6-8 × 5-8 mm, suborbicular, white, margins entire to slightly irregular, oil glands colourless. Stamens 60-80(-100 or more), free, in 4 weakly defined whorls, filaments 6-8 mm long, anthers cream, dorsifixed, latrorse. Ovary inferior, 2-3-locular, ovules numerous, in a single row on each linear placenta. Style 6-8 mm long, slender, white, stigma capitate, scarcely dilated. Fruit a broadly ovate, bright to dark red (rarely black or violet) 6-7 mm long berry. Seeds numerous, reniform, 2.0-4.3 mm diameter, testa pale brown, glossy ± smooth, very hard.

Similar Taxa

Lophomyrtus bullata differs from L. obcordata by having much larger, distinctly bullate ("bubbly") suborbicular rather than non-bullate obcordate leaves. Neomyrtus pedunculata could be confused with Lophomyrtus obcordata but it has obovate-oblong to obovate rather than obcordate leaves, and 5-merous flowers. Often in places where the ranges of Lophomyrtus bullata and L. obcordata overlap the hybrid L. ×ralphii can be found (and sometimes only this hybrid is present the parents presumably having died out for that area). Like Lophomyrtus bullata the hybrid has suborbicular leaves, only smaller (up to 16 × 12 mm), and less distinctly weakly bullate . It is fully fertile and often forms introgressive hybrid swarms. Lophomyrtus ×ralphii is popular in cultivation.

Flowering

November - March

Main Flower Colour

White

Other Flower Colour

Cream

Fruiting

January - May

Propagation Technique

Easily grown from fresh seed. Can also be grown from semi-hardwood and hardwood cuttings. Lophomyrtus obcordata is an attractive and remarkably hardy shrub that does well in a wide range of situations. of the two species in the genus, L. obcordata is more commonyl grown and sold by nuseries though even then it is still surpassed in nurseries by the diversity of freakish forms and variegated mutants derived from the hybrid L. ×ralphii (L. bullata x L. obcordata).

Threats

Not Threatened

Chromosome No.

2n = 22

Endemic Taxon

Yes

Endemic Genus

Yes

Endemic Family

No

 


      

References and further reading

de Lange, P.J.; Murray, B.G. 2004: Chromosome numbers of New Zealand Kunzea (Myrtaceae). Australian Journal of Botany 52: 609-617.

de Lange, P.J.; Datson, P.M.; Murray, B.G.; Toelken, H.R. 2005: Hybridism in the Kunzea ericoides complex (Myrtaceae): an analysis of artificial crosses. Australian Systematic Botany 18: 117-131.

de Lange, P.J.; Smissen, R.D.; Wagstaff, S.J.; Keeling, D.J.; Murray, B.G.; Toelken, H.R. 2010: A molecular phylogeny and infrageneric classification for Kunzea (Myrtaceae) inferred from rDNA ITS and ETS sequences. Australian Systematic Botany 23: 309–319.

Webb, C.J.; Simpson, M.J.A. 2001: Seeds of New Zealand Gymnosperms and Dicotyledons. Christchurch, Manuka Press.

This page last updated on 6 Dec 2014

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