NZ Myrtaceae Key - Online edition

Metrosideros colensoi Hook.f.


Common Names

akatea, rātā

Origin

New Zealand endemic.

Cultivation

Not commonly cultivated, but may be occasionally available at specialist nurseries.

Distribution

Common in limestone areas of New Zealand, from Northland (Waima Forest) south to Nelson and Marlborough, extending to Westland in the west, and south-eastern Marlborough and north-eastern Canterbury in the east. In the North Island extremely uncommon north of the Waikato and Coromandel Peninsula; in the southern part of its range mostly confined to coastal forest.

Distinguishing Features

Habit

Leafy shoots at first clinging to tree trunks via aerial roots, then unattached, slender to very slender, long-climbing, woody vines with weeping branches.

Bark and Stem/Trunk

Bark grey to pale grey, separating into thick, squarish flakes. Branchlets red-brown, 4-angled, hairy, becoming hairless with age. Adult branches weeping (pendulous).

Leaves

Leaves opposite, ranked on either side of stem and lie in one plane, although adult leaves tend to spread around the stem, ovate-lanceolate, 15–20 mm long, 7–10 mm wide, glossy to dark green above, paler below (emergent growth and juvenile leaves uniformly pale yellow-green), leaf surface flat, densely hairy when young, not puckered, midrib raised, oil glands particularly visible on lower surfaces; margins entire, hairy when young; tips pointed; stalks absent or very short.

Flowers

Flowers in small clusters crowded terminally on branches, cluster-branchlets often 3-flowered, or flowers solitary on cluster axis. Flowers ± 15 mm in diam., mature flower stalks ± 3 mm long, petals 5, rounded, ± 1.5–2.0 mm long, 1.5–2.0 mm wide, white to pink; sepals 5, tips free, persistent, stalks and base of flowers and outer surface of sepals hairy, calyx tube ± 5 mm long; stamens mostly white, filaments 8–12 mm long. Main flowering period: late spring to summer.

Fruit

Fruit dry, ± 4–5 mm wide, rounded and 3-ribbed, capsule dome occurring below the persistent calyx tube, calyx tube narrower than the fruit (± 2 mm wide), capsules split along sides to release seeds.

Similar Species

Sterile material is similar to M. diffusa, but M. colensoi differs in that the leaves are at an acute angle to the branch, juvenile leaves are pale yellow-green, distinctly hairy on the upper surface and the midvein and lateral veins are not prominently raised as opposed to leaves that are at right-angles to the branch, young upper leaf surfaces are hairless to very sparsely hairy, and the midveins and lateral veins are prominently raised. Flower clusters in M. diffusa occur laterally along branches, whereas they occur terminally in M. colensoi.

Notes

Metrosideros colensoi was given a conservation status of Threatened – Nationally Vulnerable in 2018.

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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