Lophomyrtus obcordata (Raoul) Burret

rōhutu, New Zealand myrtle

New Zealand endemic.

An attractive and hardy shrub easily propagated and commonly found in New Zealand nurseries; utilised in ornamental or shelter plantings, or occasionally for revegetation projects.

Occurring naturally throughout North and South Islands of New Zealand, mainly in coastal and lowland forested habitats, but extending to montane areas.

• Mature bark smooth, papery, grey-pink and cream, peeling in large patches.
• Leaf tips rounded with notches at the tip (making the leaves inversely heart-shaped).
• Leaves 5–12 mm long, 5–10 mm wide.
• Flowers solitary, axillary, petals and stamens white.
• Flowers with 4 petals and sepals.
• Flower and fruit stalks long.
• Fruit a spherical berry, bright to dark red, ± 5–6 mm in diam.

Branched shrub or small tree to ± 6 m tall.

Mature bark smooth, grey-pink, papery, peeling in large strips to reveal pale cream new bark. Young branchlets and stems whitish hairy, becoming hairless and reddish brown with age. Young branchlets 4-angled to begin with, then round with age.

Leaves opposite, leathery, gland-dotted, inversely heart-shaped (obcordate), ± 5–12 mm long, ± 5–10 mm wide, upper surface dark green to grey-green (sometimes tinged red), lower surface paler, leaf surface flat, not puckered, finely hairy, becoming hairless with age; margins entire; tips rounded and notched (making the leaf heart-shaped); leaf stalks short (± 1 mm long).

Flowers solitary, axillary, ± 6–8 mm in diam., flower stalks ± 10–14 mm long, petals 4, white, rounded; sepals 4, persistent, tips free, hairy; stamens numerous, white. Main flowering period: summer.

Fruit a bright to dark red, broad ovate berry, 2–3-locular, ± 6–8 mm long, ± 5–6 mm wide, seeds solitary to numerous, kidney-shaped.

Most similar to L. bullata, the only other species in the genus. The leaves that are 5–12 mm long and 5–10 mm wide, inversely heart-shaped with smooth surfaces, easily distinguish it from L. bullata, which has larger, broadly ovate to sub-orbicular leaves that are red-tinged with puckered surfaces.

Sometimes confused with Neomyrtus pedunculata, but that species has ovate to oval or oblong leaves sometimes broader away from the stalk, 4-angled branchlets and 5-parted flowers, whereas L. obcordata has heart-shaped leaves, branchlets round in cross-section, and 4-parted flowers.

Occasionally mistaken for Teucridium parvifolium which also has 4-angled branchlets, but differs in that it possesses dull, grey-green or brown-green leaves, downy young branches, tiny 5-parted flowers and dry fruit with persistent calyx in the leaf axils. All species of Coprosma differ in having tiny stipules between the pair of leaves, leaves that are neither heart-shaped nor gland-dotted and have stalkless or short-stalked fruit.

Lophomyrtus is a genus of two species (L. bullata and L. obcordata) endemic to New Zealand. Lophomyrtus ×ralphii, the naturally occurring hybrid between L. bullata and L. obcordata, and a suite of hybrid cultivars are more commonly cultivated.

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.

Myrtle rust (caused by Austropuccinia psidii) has been recorded in some natural populations of L. obcordata in New Zealand. This is concerning as (like L. bullata) L. obcordata was given a conservation status of Threatened – Nationally Critical in 2018 and faces an immediate high risk of extinction in the wild.

• Flora of New Zealand Online
• GBIF
• iNaturalist NZ
• NZPCN