NZ Myrtaceae Key - Online edition

Leptospermum scoparium J.R.Forst. & G.Forst. agg.


Common Names

kahikātoa, mānuka, tea tree

Origin

Indigenous to New Zealand. In the current sense this species is also shared with Australia, particularly Tasmania. However, there is evidence that mānuka in the strict sense is endemic to New Zealand. Further study is needed.

Cultivation

Commonly used in revegetation plantings, and in commercial plantations for oil or honey. Popular in cultivation throughout New Zealand, especially cultivars with pink, red or double flowers.

Distribution

Leptospermum scoparium var. scoparium occurs throughout New Zealand from coastal to low alpine habitats. Leptospermum scoparium var. incanum Cockayne is confined to the north of the North Island.

Distinguishing Features

  • Leaf tips usually prickly and with rough margins.
  • Flowers appearing solitary, white or sometimes pink-flushed, usually with a red centre.
  • Sepals deciduous.
  • Stamens shorter than petals.
  • Fruit woody, persistent.
  • Fruit valves forming a raised dome before opening.

Habit

Shrub or small tree to ± 12 m tall. Low growing and prostrate populations are also found in the wild.

Bark and Stem/Trunk

Bark grey, dark graphite-grey or reddish, peeling in papery flakes with reddish undersides. Young branchlets and stems hairy, becoming hairless with age.

Leaves

Adult leaves alternate, linear, narrowly elliptic or lanceolate to oblanceolate or obovate, 5–20 mm long, 1–8 mm wide, prickly to grasp, pale to dark green, leaf blade flat, leaf surfaces not puckered, hairy at first, becoming hairless, margins entire or finely scalloped, tips acute and mostly extending into a long stiff, prickly point; leaf stalks very short (sometimes appearing absent).

Flowers

Flowers solitary, axillary, (8–)10–20(–25) mm in diam., stalked, petals 5, white, sometimes pink-flushed, usually with a red centre; sepals 5, tips free, deciduous, stamens numerous, white or occasionally pinkish, shorter than the petals.

Fruit

Fruit dry, persistent, woody, 5-locular, ± 5–8 mm wide, valves domed, becoming very woody with age.

Similar Species

By the casual observer, mānuka (L. scoparium) is frequently confused with kānuka (Kunzea spp.), from which it can be easily distinguished by the hard, persistent, nut-like fruits, with non-persistent sepals, sharp-tipped leaves, and flowers which appear to be solitary.

In the context of this key, L. scoparium looks most similar to L. polygalifolium in terms of leaf length but leaves of the former are stiff and sharp-pointed, with rough leaf margins whereas leaves of the latter are slightly lemon-scented, less stiff, less sharply pointed, sometimes recurved. They also differ in that the former possess smaller fruit (5–8 mm wide) with valves each ± 2 mm wide and the latter possess larger fruit (± 6–10 mm wide) with valves each ± 4–5 mm wide; typical flowers of L. scoparium are white or pinkish and red-centred but those of L. polygalifolium are greenish to creamy white.

Notes

New Zealand L. scoparium is a very variable species. Currently there are two varieties accepted. The description above mainly applies to L. scoparium var. scoparium. Leptospermum scoparium var. incanum Cockayne is characterised by young branches, juvenile leaves and flower buds clad in long silky, grey hairs as well as pink-white or pink flowers.

Leptospermum scoparium is susceptible to myrtle rust (caused by Austropuccinia psidii). Leptospermum scoparium var. scoparium was given a conservation status of At Risk – Declining and L. scoparium var. incanum has a conservation status of Threatened – Nationally Vulnerable in 2018.

Leptospermum is a genus of about 87 species, mostly Australian, but extending to Malesia and New Zealand.

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