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Metrosideros bartlettii

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Bartlett's rātā
M. bartlettii observed by botanist Peter de Lange in 2011
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Myrtales
Family: Myrtaceae
Genus: Metrosideros
Species:
M. bartlettii
Binomial name
Metrosideros bartlettii

Metrosideros bartlettii, commonly known as the Bartlett's rātā, is one of twelve Metrosideros species in the family Myrtaceae. It is endemic to only a few parts of the Northland Region in New Zealand's North Island. Bartlett's rātā was first discovered in 1975 by New Zealand botanist and schoolteacher, John Bartlett. There are three known patches of dense native forest near Piwhane / Spirits Bay that contain Bartlett's rātā, Radar Bush, Kohuronaki Bush, and Unuwhao Bush. Bartlett's rātā has a high chance of going extinct unless immediate conservation measures are taken due to its ongoing decline. It is notable for its rarity and white flowers. As of 2018, only 13 adult trees are known to exist in the wild.

Description

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Leafage of a tree
Foliage of Bartlett's rātā (M. bartlettii) in Ōtari-Wilton's Bush

Metrosideros bartlettii (Bartlett's rātā) is a rare tree endemic to the Northland Region of the North Island of New Zealand. It grows to a height of up to 25 m (82 ft) with a trunk up to 1 m (3 ft 3 in) in diameter, twigs are often coloured dark red. Its bark is pale grey to whitish in colour. Its leaves are chartaceous to coriaceous in character, glossy, palish-green in colour and its lamina being 30–50 × 15–26 mm long. There are 3–4 pairs of cymules (very small flowers) on an inflorescence with densely spreading white hairs. Its flowers are unique; they are coloured white with pedicels of up to 3 x 1 , 2.5–3 mm high, 2–2.5 mm wide, and spreading 1–1.5 x 1–1.5 mm.[2][3]

Taxonomy

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It was first discovered in 1975 by New Zealander John Bartlett in Radar Bush, 9.5 km (5.9 mi) south east from Cape Reinga,[4][3] a schoolteacher and botanist from Hamilton.[5] It was discovered by Bartlett was searching for liverworts in the Northland Region of New Zealand, untill he found a specimen growing at the base of a large tree. He realised it was a new species of rātā, but was unable to reach any branches so he instead took fragments of the bark to the Victoria University of Wellington and to botanist John Dawson, who incorrectly thought the find was northern rātā (M. robusta). Bartlett later returned to the area and was able collect a branch and later took it to Wellington.[6] Bartlett's rātā is closely related to northern rātā (M. robusta),[7] its leaves are of similar size and share characteristics to southern rātā (M. umbelata) and northen rātā. Bartlett's rātā's flowers are significantly smaller than those of northern rātā. M. oreomyrtus, endemic to New Caledonia, is the only other tree in the genus Metrosideros with white-coloured flowers.[2]

Distribution

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Bartlett's rātā is endemic to New Zealand's North Island to the Northland Region. It is only known to be located in Te Paki, in three patches of forest remnants near Piwhane / Spirits Bay. These being, Kohuronaki Bush, Radar Bush, and Unuwhao Bush.[7] It is usually found growing near bodies of water (such as streams) and in swamps.[8] An article from Molecular Ecology published in 2000, documented 31 adult trees.[4] A 2018 report has since documented only 13 adult trees.[9] Bartlett's rātā was likely never a common tree, with extensive surveys conducted in the 1990s revealed individuals were only present in three populations.[10]

Conservation

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Its current conservation status was assesed by the IUCN Red List in 2013 as "Critically Endangered" and its population trend as "Decreasing".[1] Bartlett's rātā largest historical decline is largely due to land use changes following settlement, and the introduction of brushtail possums (an invasive species in New Zealand).[11][12] It is common in cultivation, with it being found in several private and botanic gardens throughout the country (such as Ōtari-Wilton's Bush, in Wellington).[9]

Bartlett's rātā has a high chance of going extinct, unless immediate conservation measures are taken due to its ongoing decline, population size, and reproductive failure. Its breeding strategy favours cross-pollination, and has very little inbreeding. Bartlett's rātā under cultivation has a low level of genetic variety, might restrict its ability to contribute to the its overall conservation.[13]

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  • Close up of Bartlett's rātā's white-coloured flowers
    Close up of Bartlett's rātā's white-coloured flowers
  • Bark of Bartlett's rātā
    Bark of Bartlett's rātā
  • Young specimen in Auckland, New Zealand
    Young specimen in Auckland, New Zealand

See also

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References

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Citations

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  1. ^ a b De Lange 2014.
  2. ^ a b Dawson 1985.
  3. ^ a b Bercusson & Torrence 1998, p. 67.
  4. ^ a b Drummond et al. 2000, p. 1.
  5. ^ Galloway & Edgar 1987, p. 2.
  6. ^ Judd 2000.
  7. ^ a b De Lange 2024.
  8. ^ Dawson 1985, p. 2.
  9. ^ a b Nadarajan et al. 2021, pp. 2–3.
  10. ^ Nadarajan et al. 2021, p. 1.
  11. ^ Van der Walt, Alderton-Moss & Lehnebach 2022, p. 2.
  12. ^ Pattabiraman et al. 2022, p. 3.
  13. ^ Van der Walt, Alderton-Moss & Lehnebach 2022, p. 9.

Works cited

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Journals

Miscellaneous

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