NZ Myrtaceae Key - Online edition

Metrosideros albiflora Sol. ex Gaertn.


Common Names

akatea, large white rātā, Northland white rātā

Origin

New Zealand endemic.

Cultivation

Uncommon in cultivation due to difficulties in propagation. Metrosideros albiflora is sensitive to cold and this limits its use as a garden plant across New Zealand. Occasionally available from specialist plant nurseries.

Distribution

A sparsely distributed species of coastal to montane kauri (Agathis australis) forest in the northern North Island. Within this area it is most common south of Kaitaia (it is not known north of there) in central and western Northland, on Aotea / Great Barrier Island and the Coromandel Peninsula. Otherwise known from scattered locations in the northern Kaimai Range and northern Waikato. Apparently absent from the Auckland Region.

Distinguishing Features

Habit

Stout climber up to ± 20 m when supported, or less commonly as a semi-climbing shrub.

Bark and Stem/Trunk

Bark initially brown, grey with age, may be fragmented into small thick flakes. Branchlets round, hairy at first, becoming hairless with age.

Leaves

Adult leaves arranged in opposite pairs, each pair being at right angles to the pair below, leathery, ovate to elliptic to broadly lanceolate, 35–90 mm long, 20–35(–46) mm wide, upper surface darkish green, usually glossy, lower surface paler, leaf surface flat, upper and lower surfaces hairless, oil glands not readily visible to the naked eye, but easier to see on the lower surface; margins entire, tips abruptly pointed, leaf stalks 2–6 mm long, stout, hairy.

Flowers

Flowers in grape-like bunches of 6–10, borne terminally or axillary, flowers ± 6–7 mm in diam., flower stalks ± 3–5 mm long, petals 5, white, orbicular, ± 5 × 5 mm; sepals 5, tips free, persistent, hairless (apart from hairy sepal margins); stamens white, filaments 15–30 mm long, much longer than petals. Main flowering period: late winter to spring.

Fruit

Fruit dry, urn-shaped, ± 5–10 mm wide, capsule dome occurring below the persistent calyx tube, calyx tube narrower than the fruit (± 2 mm wide), capsule splits along sides to release seeds.

Similar Species

Distinguishable from the other white-flowered Metrosideros vine species (M. colensoi, M. diffusa and M. perforata) by the much larger adult leaves, ≥ 35 mm long and by the stamen filaments 15–30 mm long as opposed to leaves <25 mm long and stamen filaments ± 10 mm long. The juvenile foliage of M. albiflora could be confused with M. carminea and M. perforata. Like M. carminea the leaves are softly hairy but the emergent leaves are pale to dark green never flushed pink; like M. perforata the leaf surfaces are prominently gland spotted but the leaves of M. perforata are hairless and leathery, those of M. albiflora are soft and hairy.

Notes

Metrosideros albiflora is believed susceptible to myrtle rust (caused by Austropuccinia psidii) so it has received a precautionary threat assessment of Threatened – Nationally Vulnerable.

Metrosideros is a genus of more than 50 species of trees, shrubs and vines, mostly found in the Pacific region. New Zealand is well represented by having 12 endemic species.

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