Metrosideros bartlettii

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File:Foliage of a cultivated Bartlett's rātā individual.jpg

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Metrosideros bartlettii (Bartlett's rātā) is a tree in the family Myrtaceae,{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=1}}{{sfn|De Lange|2024}} reaching a height of up to {{convert|30|m|abbr=off|sigfig=1}} with a trunk up to 1–1.5 m in diameter. Its bark is described as "papery" and is pale grey to whitish in colour, shedding freely, and separating into soft flakes. Its young twigs are often coloured dark red.{{Sfnm|Dawson|1985|1p=1|De Lange|2024}}{{Sfn|Wassilieff|2007}}

The leaves are chartaceous (paper-like) to coriaceous (leather-like) in character with laminae (leaf blades) that are 30–50 mm long × 15–23 mm wide. Young leaves are palish-green to yellow-green and become dark green as they mature. The leaves' upper surfaces are shiny, and their lower surfaces are glossy. There are 3–4 pairs of cymules (very small flowers) on an inflorescence (flower cluster) with densely spreading white hairs.{{Sfnm|Dawson|1985|1p=1|De Lange|2024}}{{Sfn|Wassilieff|2007}}

Compared to other species in the genus Metrosideros, the flowering of Bartlett's rātā is unpredictable, making it unlikely its small population can regenerate naturally.{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|p=3}} Bartlett's rātā typically flowers in spring, from October to November; the species produces distinct white-coloured flowers with pedicels up to 3 × 1 mm and a hypanthium of up to 2.5–3 mm high × 2–2.5 mm wide. Its spreading sepals are triangle-shaped and are 1–1.5 × 1–1.5 mm long, and its petals are elliptical to egg-shaped and are 2.5–3 × 1.8–2 mm long. Its peduncles are 9 × 1 mm long. Its stamens are 5–9 mm long, and the styles are slightly longer at 10–11 mm long. Its petioles are 4–5 × 1 mm long.{{Sfnm|Dawson|1985|1p=1|De Lange|2024}}{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|p=3}}

From March to April, Bartlett's rātā produces small puberulent hypanthium fruits about 2.0–2.5 mm high × 2.5–3.0 mm wide, with persistent, deflexed (bent downwards) sepals and 1.5–2.5 mm long capsules. The pale orange-yellow seeds Bartlett's rātā produces are 2.3–3.0 mm long, narrowly elliptic to narrowly oval-shaped, and are straight or slightly curved.{{Sfn|De Lange|2024}}

The leaves of Bartlett's rātā have a size similar to northern rātā (M. robusta) and southern rātā (M. umbellata). The flowers of Bartlett's rātā are distinguished from those of northern rātā by their pure white colour and smaller size. Bartlett's rātā is also the only New Zealand species in the genus Metrosideros with such easily detachable and paper-like bark.{{Sfnm|Dawson|1985|1pp=2–3|De Lange|2024}}

{{cladogram|align=right|title=

|caption=Cladogram depicting the phylogeny and relationships of selected species within the genus Metrosideros in the clade "Va".{{sfn|Wright|Liddell|Lacap‐Bugler|Gillman|2021|p=1}}{{legend|blue|East Polynesia ({{abbr|incl.|including}} Kermadec)}}{{legend|crimson|New Zealand ({{abbr|excl.|excluding}} Kermadec)}}

|clades={{clade| style=font-size:85%;line-height:85%;width:235px;

|label1=    

|1={{clade

|label2=

|1={{clade

|label2=    

|2=M. bartlettii|bar2=crimson

|1={{clade

|1={{clade

|1=M. tremuloides|bar1=blue

|2=M. collina|bar2=blue

|3=M. polymorpha|bar3=blue

|4=M. macropus|bar4=blue

|5=M. macropus|bar5=blue

|6=M. rugosa|bar6=blue

}}

|2={{clade

|1=M. collina (Tahiti)|bar1=blue

|2=M. collina (Cook Islands)|bar2=blue

|3=M. collina (Rūrutu)|bar3=blue

}}

|3=M. exclesa|bar3=crimson

|4=M. nervulosa|bar4=blue

|5=M. kermadecensis|bar5=blue

|6=M. sclerocarpa|bar6=blue

|7=M. robusta|bar7=crimson

}}}}}}}}}}

Metrosideros bartlettii is categorised in the subgenus Metrosideros within the genus Metrosideros,{{sfn|Bylsma|Clarkson|Efford|2014|p=5}} which consists of about 58 described species across Africa, Asia, Oceania and South America.{{sfn|Wright|Liddell|Lacap‐Bugler|Gillman|2021|p=1}}{{sfn|Pillon|Lucas|Johansen|Sakishima|2015|p=1}} The genus consists of two main subgenera: Metrosideros (trees) and Mearnsia (vines and shrubs).{{sfn|Wright|Liddell|Lacap‐Bugler|Gillman|2021|p=1}}{{sfn|Bylsma|Clarkson|Efford|2014|p=5}} There are twelve known species of Metrosideros in New Zealand; the subgenus Metrosideros comprises five tree species, M. bartlettii, M. excelsa, M. kermadecensis, M. robusta, and M. umbellata; the other superseeded subgenus, Mearnsia, comprises six vine species and one shrub, M. albiflora, M. carminea, M. colensoi, M. diffusa, M. fulgens, M. perforata, and M. parkinsonii.{{sfn|Bylsma|Clarkson|Efford|2014|p=5}}{{sfn|Connor|Edgar|1987|p=20}}

In 2021, a cladistic analysis from Austral Ecology of the genus Metrosideros, indicated a dispersal and radiation of the Metrosideros subgenus from New Zealand to Polynesia, Lord Howe Island and the Kermadec Islands. Their analysis, using rDNA sequencing, suggested the phylogenetic relationships within this subclade suggested a separate dispersal route into East Polynesia, including "an apparent step" from the Marquesas Islands to Hawaii. Metrosideros bartlettii and its related species are categorised in the clade (group) "Va". This clade includes two of its closest New Zealand relatives, M. excelsa and M. robusta, as well as various species from East Polynesia (including Hawaii), Lord Howe Island and the Kermadec Islands.{{sfn|Wright|Liddell|Lacap‐Bugler|Gillman|2021|pp=1–5}}

Bartlett's rātā was accidentally discovered in 1975 by the New Zealand botanist and schoolteacher John Bartlett while searching for liverworts near Cape Reinga.{{Sfn|Wassilieff|2007}}{{Sfn|Galloway|Edgar|1987|p=2}} He came across the species growing at the base of a large tree in Radar Bush, near Cape Reinga.{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=1}}{{Sfn|Bercusson|Torrence|1998|p=67}} Bartlett realised it was a new species of rātā but was unable to reach any of the branches, so he instead took fragments of the bark to botanist John Dawson of the Victoria University of Wellington. Dawson thought the find was northern rātā, but Bartlett believed it was a new species, so he later returned to the area where he found the species and was able to collect a branch by shooting one off with his rifle. He then took the branch back to Wellington.{{Sfn|Judd|2000}}{{Sfn|Ringham|2023|p=5}}

Dawson described the new species in a 1985 article in the New Zealand Journal of Botany,{{sfnm|IPNI|2025|Dawson|1985|2p=1}} noting it had a "distinct whitish, spongy bark and small white flowers" and when flowers of Bartlett's rātā were first collected in 1984, it was clear to him that "a new species was involved". The examined type material for the article was collected in July 1978 by John Bartlett in Radar Bush and the isotype was collected in November 1984 by Nigel Culnie near Spirits Bay Road.{{Sfn|Dawson|1985|pp=1–4}}{{NoteTag|An image of the herbarium specimen (isotype) can be found in the "Museum of New Zealand Te Papa Tongarewa" link located here.}}

The etymology (word origin) of Bartlett's rātā's genus Metrosideros translates to English from Greek as 'iron heart'; the word {{lang|el|metra}} means 'core' or 'heart', and {{lang|el|sideron}} means 'iron'.{{Sfn|De Lange|2024}}{{sfn|Bylsma|Clarkson|Efford|2014|p=4}} The specific epithet (second part of the scientific name), bartlettii, is named after the species' discoverer, John Bartlett.{{Sfn|Dawson|1985|p=1}} The species is commonly known as 'Bartlett's rātā' and 'rātā Moehau'; a name originating from the Māori language.{{sfnm|De Lange|2014|Ringham|2023|2p=5}}{{NoteTag|'Moehau' is the name of a traditional ancestor and should therefore be capitalised. However, some sources do not capitalise it.}} Bartlett's rātā's Māori name was given by Ngāti Kurī elders in 1975 in honour of Moehau, an important ancestor for the Ngāti Kurī iwi (tribe).{{Sfn|Ringham|2023|pp=3–5}}

File:Bartlett's Rātā (Metrosideros bartletti) in November (cropped).jpg

The flowers of Bartlett's rātā are observed to be frequently visited by birds and insects (such as bees and flies), which may help spread pollen to Bartlett's rātā from other nearby Metrosideros individuals.{{sfn|Mochizuki|Yoneda|Yamanaka|2024|p=6}}{{sfn|Van der Walt|Alderton-Moss|Lehnebach|2022|p=8}} Despite this, it is unclear what the primary pollinators of Bartlett's rātā are.{{sfn|Mochizuki|Yoneda|Yamanaka|2024|p=6}} Introduced species are known to visit Metrosideros in a manner similar to native species. This could be due to the inherent vulnerability of biotas on isolated oceanic islands to disruption by introduced species.{{sfn|Mochizuki|Yoneda|Yamanaka|2024|p=6}}

In 2018, two New Zealand botanists, Carlos Lehnebach and Karin van der Walt, examined the pollination and the flower development of Bartlett's rātā. In their study, published in the New Zealand Plant Conservation Network, they found that Bartlett's rātā is a self-incompatible tree, meaning that its flowers will only seed if it is pollinated by pollen from a genetically distinct tree.{{Sfn|Lehnebach|Van der Walt|2018|pp=2–3}} In 2021, the New Zealand Journal of Botany published a similar study in which researchers and scientists analysed the ex situ conservation of Bartlett's rātā individuals at Ōtari-Wilton's Bush. Their analyses confirmed the self-incompatibility of Bartlett's rātā, which is consistent with other species within the genus Metrosideros. Although it was speculated that self-incompatibility occurred in Bartlett's rātā, it had never been experimentally confirmed until these two studies.{{NoteTag|The two researchers from the 2018 study, Carlos Lehnebach and Karin van der Walt,{{Sfn|Lehnebach|Van der Walt|2018|p=2}} were also involved in the 2021 research article in the New Zealand Journal of Botany, together with Jayanthi Nadarajan, Hassan Saeiahagh and Ranjith Pathirana.{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|p=1}}}} In their 2021 analyses, hand-pollination of Bartlett's rātā individuals produced seeds with generally low germination rates; this biological finding is consistent with other species in the family Myrtaceae, such as pōhutukawa and mānuka (Leptospermum scoparium).{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|pp=8, 14}} Their analyses also confirmed that hybridisation between Bartlett's rātā and pōhutukawa resulted in capsule formations; however, the seeds from their analyses had "very low" viability.{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|pp=8, 14}}{{sfn|Van der Walt|Alderton-Moss|Lehnebach|2022|pp=2, 6–8}}

A 2022 research article on the cross-pollination of cultivated Bartlett's rātā individuals, published in the Pacific Conservation Biology, revealed that cross-pollination is the only viable method that produces seeds that can be used in naturalised populations. The research article also revealed that the flower development of Bartlett's rātā is characterised by dichogamy, which is a method to prevent self-pollination by having stigma receptivity and release of pollen occur sequentially, i.e., not at the same time. Their study found that Bartlett's rātā's breeding strategy favours cross-pollination and has very little inbreeding.{{sfn|Van der Walt|Alderton-Moss|Lehnebach|2022|pp=2, 6–8}}{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|p=8}}

The endemic liverwort species Frullania wairua and Siphonolejeunea raharaha-nehemiae, both at risk of extinction, are known to be hosted by Bartlett's rātā.{{Sfn|De Lange|2024}}{{sfn|Von Konrat|Braggins|2005|p=7}} Anthracophyllum archeri, a species of fungus in the family Omphalotaceae and other fungi in the genus Cladobotryum, were also observed to be growing on the bark and the fallen twigs of Bartlett's rātā in native forest in Te Paki, Northland.{{sfn|McKenzie|Buchanan|Johnston|1999|pp=7, 16}}{{sfn|Segedin|1994|pp=7–8}}

Bartlett's rātā is endemic to the Northland Region in New Zealand's North Island. Its range covers the northern tip of the Aupōuri Peninsula, in three patches of dense forest remnants near Piwhane / Spirits Bay, these being: Kohuronaki Bush, Radar Bush, and Unuwhao Bush.{{Sfnm|De Lange|2024|Strongman|2017}}{{sfn|Drummond|Keeling|Richardson|Gardner|2000|pp=1, 8}} At the time of the original species description in 1985, only seven naturalised adult individuals were known to be located at two of the sites. Later in the mid-1990s, New Zealand's Department of Conservation recorded nineteen adult individuals. Then, a 2000 research article of Bartlett's rātā, published in Molecular Ecology, revealed an additional twelve adult individuals, bringing the known species count of Bartlett's rātā to thirty-one in the year 2000.{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=1}}

Before a DNA profiling test of Bartlett's rātā individuals was conducted in 2015, the Department of Conservation was unaware that three of the five genotypes required to grow genetically suitable trees were located within the tribal territories of the Ngāti Kurī and Te Aupōuri iwi. At most, five of the fourteen trees in 2015 possessed the unique genotypes required for the genetic diversity, which is essential to the species' existence. New Zealand botanist and science advisor Peter de Lange stated that without intervention "the future was bleak" for Bartlett's rātā.{{Sfn|Cook|2016}} The 2018 article by Lehnebach and Van der Walt, published by the New Zealand Plant Conservation Network, has since reported only thirteen adult trees in the wild.{{Sfn|Lehnebach|Van der Walt|2018|pp=2–3}}{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|pp=2–3}}

Bartlett's rātā is usually found growing near bodies of water, such as streams and swamps.{{Sfn|Dawson|1985|p=2}} Bartlett's rātā's habitat favours dense lowland forests; the plant usually germinates and begins life as an epiphyte (growing on another plant), specimens have been observed growing on: pūriri (Vitex lucens), rewarewa (Knightia excelsa), taraire (Beilschmiedia tarairi), and tree ferns (Cyathea). Bartlett's rātā have occasionally been observed growing on boulders, cliff sides, and rock outcrops.{{Sfnm|De Lange|2014|Dawson|1985|2p=2}}{{Sfn|Bercusson|Torrence|1998|p=41}}

File:Common Brushtail Possum - Flickr - GregTheBusker (1).jpg is one cause of the historical decline of Bartlett's rātā.|alt=A common brushtail possum photographed on the ground and at night.]]

Bartlett's rātā is one of New Zealand's most threatened and rarest trees.{{sfn|Van der Walt|Alderton-Moss|Lehnebach|2022|pp=1–2}}{{Sfn|Stowell|2017}} Its conservation status was assessed by the IUCN Red List in 2013 as critically endangered, and its population trend was evaluated as decreasing.{{Sfn|De Lange|2014}} Its assessment in the New Zealand Threat Classification System was evaluated in 2023 as nationally critical.{{Sfn|New Zealand Threat Classification System 2023}} The decline of Bartlett's rātā is attributed to land use changes following human settlement and the introduction of common brushtail possums,{{Sfn|Cook|2016}}{{sfn|Van der Walt|Alderton-Moss|Lehnebach|2022|pp=1–2}} an invasive species in New Zealand, which browse its buds, flowers, and shoots.{{sfn|Van der Walt|Alderton-Moss|Lehnebach|2022|pp=1–2}}{{sfn|Moinet|Rogers|Biggs|Marshall|2024|p=1}} Another threat to Bartlett's rātā is myrtle rust, a type of plant disease that infects many species in the family Myrtaceae, including Bartlett's rātā.{{sfn|Van der Walt|Alderton-Moss|Lehnebach|2022|pp=1–2}}{{sfn|Toome-Heller|Ho|Ganley|Elliott|2020|pp=221–230}} Although Bartlett's rātā is uncommon in the wild, it is common in cultivation and is found in several private and botanic gardens across the country.{{Sfn|Lehnebach|Van der Walt|2018|pp=2–3}}{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|pp=2–3}}

The habitat disturbance of Bartlett's rātā began with the arrival of the first human settlers from East Polynesia in {{circa}} 1250 – 1300 CE.{{Sfn|Wilson|2005}}{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=8}} Later in the 1800s, New Zealand experienced the arrival of European settlers, who cleared many forests, contributing to the habitat disturbance of Bartlett's rātā. Although the forests in Northland are gradually recovering, the population of Bartlett's rātā remains low and is scattered between three known locations near Piwhane / Spirits Bay.{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=8}}

Unless immediate conservation measures are taken, Bartlett's rātā has a high chance of becoming extinct due to its ongoing decline, small population size, and reproductive failure.{{sfn|Van der Walt|Alderton-Moss|Lehnebach|2022|p=9}}{{Sfnm|Stowell|2017|De Lange|2024}} In 2020, the Ngāti Kurī iwi established a planting programme in collaboration with Manaaki Whenua – Landcare Research with the aim of increasing and protecting the number of Bartlett's rātā trees remaining in the wild.{{sfnm|Gibbson|2022|Ringham|2023|2p=5}} {{as of|January 2024}}, there has been over five hundred new plantings of Bartlett's rātā in Cape Reinga. The programme aims to increase the number of individuals to four thousand.{{Sfn|Radio New Zealand|2024}}

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Journals

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• {{cite journal |last=Bylsma |first=Rj |last2=Clarkson |first2=Bd |last3=Efford |first3=Jt |title=Biological flora of New Zealand 14: Metrosideros excelsa, pōhutukawa, New Zealand Christmas tree |url=https://www.tandfonline.com/doi/full/10.1080/0028825X.2014.926278 |journal=New Zealand Journal of Botany |volume=52 |issue=3 |date=3 July 2014 |issn=0028-825X |doi=10.1080/0028825X.2014.926278 |doi-access=free |pages=365–385}}
• {{cite journal | last=Connor | first=H. E. | last2=Edgar | first2=E. | title=Name changes in the indigenous New Zealand flora, 1960–1986 and Nomina Nova IV, 1983–1986 |url=https://www.tandfonline.com/doi/abs/10.1080/0028825X.1987.10409961 | journal=New Zealand Journal of Botany | volume=25 | issue=1 | date=1987 | issn=0028-825X | doi=10.1080/0028825X.1987.10409961 |doi-access=free | pages=115–171}}
• {{cite journal |doi=10.1080/0028825X.1985.10434231 |title=Metrosideros bartlettii (Myrtaceae) a new species from North Cape, New Zealand |url=https://www.tandfonline.com/doi/abs/10.1080/0028825X.1985.10434231 |issn=0028-825X |doi-access=free |year=1985 |last1=Dawson |first1=J. W. |journal=New Zealand Journal of Botany |volume=23 |issue=4 |pages=607–610 }}
• {{cite journal |doi=10.1046/j.1365-294x.2000.00989.x|title=Genetic analysis and conservation of 31 surviving individuals of a rare New Zealand tree, Metrosideros bartlettii (Myrtaceae) |url=https://onlinelibrary.wiley.com/doi/10.1046/j.1365-294x.2000.00989.x |url-access=subscription |year=2000|last1=Drummond|first1=R. S. M.|last2=Keeling|first2=D. J.|last3=Richardson|first3=T. E.|last4=Gardner|first4=R. C.|last5=Wright|first5=S. D.|journal=Molecular Ecology|volume=9|issue=8|pages=1149–1157|issn=0962-1083}}
• {{cite journal |last1=Galloway |first1=D. J. |last2=Edgar |first2=Elizabeth |title=Obituaries |journal=New Zealand Journal of Botany |volume=25 |issue=1 |year=1987 |pages=173–178 |url=https://www.tandfonline.com/doi/pdf/10.1080/0028825X.1987.10409963| access-date=25 December 2024 |issn=0028-825X |doi=10.1080/0028825X.1987.10409963 |doi-access=free}}
• {{cite journal |last=McKenzie |first=E. H. C. |last2=Buchanan |first2=P. K. |last3=Johnston |first3=P. R. |title=Fungi on pohutukawa and other Metrosideros species in New Zealand |journal=New Zealand Journal of Botany |volume=37 |issue=2 |date=1999 |issn=0028-825X |doi=10.1080/0028825X.1999.9512637 |doi-access=free |pages=335–354 |url=https://www.tandfonline.com/doi/pdf/10.1080/0028825X.1999.9512637 |access-date=22 January 2025}}
• {{cite journal |last=Mochizuki |first=Ko |last2=Yoneda |first2=Kaoru |last3=Yamanaka |first3=Masumi |title=1109. Metrosideros boninensis (Hayata ex Koidz.) Tuyama: Myrtaceae |journal=Curtis's Botanical Magazine |volume=41 |issue=3 |date=2024 |issn=1355-4905 |eissn=1467-8748 |doi=10.1111/curt.12591 |doi-access=free |pages=323–330}}
• {{cite journal |last=Moinet |first=Marie |last2=Rogers |first2=Lynn |last3=Biggs |first3=Patrick |last4=Marshall |first4=Jonathan |last5=Muirhead |first5=Richard |last6=Devane |first6=Megan |last7=Stott |first7=Rebecca |last8=Cookson |first8=Adrian |title=High-resolution genomic analysis to investigate the impact of the invasive brushtail possum (Trichosurus vulpecula) and other wildlife on microbial water quality assessments |journal=PLOS One |volume=19 |issue=1 |date=18 January 2024 |issn=1932-6203 |doi=10.1371/journal.pone.0295529 |doi-access=free |page=e0295529}}
• {{cite journal |last=Nadarajan |first=Jayanthi |last2=van der Walt |first2=Karin |last3=Lehnebach |first3=Carlos A. |last4=Saeiahagh |first4=Hassan |last5=Pathirana |first5=Ranjith |title=Integrated ex situ conservation strategies for endangered New Zealand Myrtaceae species |journal=New Zealand Journal of Botany |volume=59 |issue=1 |date=2 January 2021 |issn=0028-825X |doi=10.1080/0028825X.2020.1754245 |url=https://www.tandfonline.com/doi/full/10.1080/0028825X.2020.1754245 |doi-access=free |pages=72–89}}
• {{cite journal | last=Pillon | first=Yohan | last2=Lucas | first2=Eve | last3=Johansen | first3=Jennifer B. | last4=Sakishima | first4=Tomoko | last5=Hall | first5=Brian | last6=Geib | first6=Scott M. | last7=Stacy | first7=Elizabeth A. | title=An expanded Metrosideros (Myrtaceae) to include Carpolepis and Tepualia based on nuclear genes | journal=Systematic Botany | publisher=American Society of Plant Taxonomists | volume=40 | issue=3 | year=2015 | issn=03636445 | jstor=24546499 | pages=782–790 | url=http://www.jstor.org/stable/24546499 |url-access=subscription | access-date=12 February 2025}}
• {{cite journal |last=Ringham |first=Sandi |title=Mana Wahine reworking the power to name taonga |journal=New Zealand Geographer |volume=79 |issue=3 |date=2023 |issn=0028-8144 |doi=10.1111/nzg.12378 |doi-access=free |pages=181–189 |url=https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/nzg.12378 |access-date=16 January 2025|hdl=10289/16228 |hdl-access=free }}
• {{cite journal | last=Segedin | first=Barbara P. | title=Studies in the Agaricales of New Zealand: new records and new species of the genera Cheimonophyllum, Mniopetalum, and Anthracophyllum (Tricholomataceae, Collybieae) |url=https://www.tandfonline.com/doi/abs/10.1080/0028825X.1994.10410407 |doi=10.1080/0028825X.1994.10410407 |doi-access=free | journal=New Zealand Journal of Botany | volume=32 | issue=1 | date=1994 | issn=0028-825X | pages=61–72}}
• {{cite journal |last=Toome-Heller |first=M. |last2=Ho |first2=W. W. H. |last3=Ganley |first3=R. J. |last4=Elliott |first4=C. E. A. |last5=Quinn |first5=B. |last6=Pearson |first6=H. G. |last7=Alexander |first7=B. J. R. |title=Chasing myrtle rust in New Zealand: host range and distribution over the first year after invasion |journal=Australasian Plant Pathology |volume=49 |issue=3 |date=2020 |issn=0815-3191 |doi=10.1007/s13313-020-00694-9 |doi-access=free |pages=221–230 |url=https://link.springer.com/content/pdf/10.1007/s13313-020-00694-9.pdf |access-date=3 February 2025}}
• {{cite journal |last=Van der Walt |first=Karin |last2=Alderton-Moss |first2=Jennifer |last3=Lehnebach |first3=Carlos A. |title=Cross-pollination and pollen storage to assist conservation of Metrosideros bartlettii (Myrtaceae), a critically endangered tree from Aotearoa New Zealand |journal=Pacific Conservation Biology |volume=29 |issue=2 |date=1 March 2022 |issn=1038-2097 |doi=10.1071/PC21054 |doi-access=free |pages=141–152 |url=https://www.publish.csiro.au/pc/pdf/PC21054 |access-date=17 December 2024}}
• {{cite journal |last=Von Konrat |first=M. J. |last2=Braggins |first2=J. E. |title=Frullania wairua, a new and seemingly rare liverwort species from Northland, New Zealand |journal=New Zealand Journal of Botany |volume=43 |issue=4 |date=2005 |issn=0028-825X |doi=10.1080/0028825X.2005.9512998 |doi-access=free |pages=885–893 |url=https://www.tandfonline.com/doi/pdf/10.1080/0028825X.2005.9512998 |access-date=20 January 2025}}
• {{cite journal | last=Wright | first=Shane D. | last2=Liddell | first2=Luke G. | last3=Lacap‐Bugler | first3=Donnabella C. | last4=Gillman | first4=Len N. | title=Metrosideros (Myrtaceae) in Oceania: Origin, evolution and dispersal |url=https://onlinelibrary.wiley.com/doi/10.1111/aec.13053 |url-access=subscription | journal=Austral Ecology | volume=46 | issue=8 | date=2021 | issn=1442-9985 | doi=10.1111/aec.13053 | pages=1211–1220}}

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Miscellaneous

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• {{Cite book |title=Pohutukawa: tree of Aotearoa |last=Bercusson |first=Linda |publisher=Tandem Press |year=1998 |isbn=9781877178351 |location=Auckland, New Zealand |url=https://archive.org/details/pohutukawatreeof0000berc |url-access=registration |last2=Torrence |first2=Jacinda |via=the Internet Archive}}
• {{Cite news |title=Fight to save New Zealand's most threatened tree |last=Cook |first=Alexa |date=14 January 2016 |url=https://www.rnz.co.nz/news/national/294088/fight-to-save-nz's-most-threatened-tree |url-status=live |archive-url=https://web.archive.org/web/20210515110036/https://www.rnz.co.nz/news/national/294088/fight-to-save-nz's-most-threatened-tree |archive-date=15 May 2021 |access-date=10 February 2025 |work=Radio New Zealand |issn=1179-6251}}
• {{cite web|url= https://dx.doi.org/10.2305/IUCN.UK.2014-2.RLTS.T34295A62743272.en |doi=10.2305/IUCN.UK.2014-2.RLTS.T34295A62743272.en |archive-url=https://web.archive.org/web/20240120102557/https://www.iucnredlist.org/species/34295/62743272 |doi-access=free |archive-date=20 January 2024 |url-status=live |last=De Lange|first=Peter|date=2014|website=IUCN Red List |title=Bartlett's Rata, Metrosideros bartlettii |access-date=17 December 2024}}
• {{Cite web |title=Metrosideros bartlettii |url=https://www.nzpcn.org.nz/flora/species/metrosideros-bartlettii/ |archive-url=https://web.archive.org/web/20241203002702/https://www.nzpcn.org.nz/flora/species/metrosideros-bartlettii/ |archive-date=3 December 2024 |url-status=deviated |last=De Lange |first=Peter |access-date=30 December 2024 |website=New Zealand Plant Conservation Network |year=2024}}
• {{Cite web |title=Ngāti Kuri's conservation vision in the Far North boosted by involvement in Ngā Rākau Taketake |url=https://bioheritage.nz/ngati-kuris-conservation-vision-in-the-far-north-boosted-by-involvement-in-nga-rakau-taketake/ |last=Gibbson |first=Jacqui |date=20 December 2022 |url-status=live |archive-url=https://web.archive.org/web/20230201044052/https://bioheritage.nz/ngati-kuris-conservation-vision-in-the-far-north-boosted-by-involvement-in-nga-rakau-taketake/ |archive-date=1 February 2023 |access-date=3 February 2025 |website=Biological Heritage New Zealand |via=Manaaki Whenua – Landcare Research}}
• {{Cite news |title=Rata: an export success |last=Judd |first=Warren |url=https://www.nzgeo.com/stories/rata-an-export-success/ |archive-url=https://web.archive.org/web/20240303070426/https://www.nzgeo.com/stories/rata-an-export-success/ |url-access=limited |archive-date=3 March 2024 |url-status=live|access-date=30 December 2024 |work=New Zealand Geographic |date=1 September 2000 |issue=47 |issn=0113-9967}}
• {{Cite news |title=About the birds and the bees and the flowers of Bartlett's rātā; pollination studies to assist conservation of a threatened—nationally critical species. |publisher=Trilpedia |url=https://www.nzpcn.org.nz/site/assets/files/0/51/296/trilepidea-172-180331.pdf |archive-url=https://web.archive.org/web/20220618180236/https://www.nzpcn.org.nz/site/assets/files/0/51/296/trilepidea-172-180331.pdf |archive-date=18 June 2022 |url-status=live |last=Lehnebach |first=Carlos A. |volume=172 |pages=2–3 |last2=Van der Walt |first2=K. |year=2018 |via=the New Zealand Plant Conservation Network}}
• {{Cite news |title=Rare tree flowers at Virginia Lake |last=Stowell |first=Laurel |date=25 November 2017 |url=https://www.nzherald.co.nz/whanganui-chronicle/news/rare-tree-flowers-at-virginia-lake/SPJYXCTX6W46KT2YVYXP2LNTZU/ |archive-url=https://web.archive.org/web/20241218021400/https://www.nzherald.co.nz/whanganui-chronicle/news/rare-tree-flowers-at-virginia-lake/SPJYXCTX6W46KT2YVYXP2LNTZU/#expand |archive-date=18 December 2024 |url-status=live|access-date=30 December 2024 |publisher=Whanganui Chronicle |work=New Zealand Herald |issn=1170-0777 }}
• {{Cite news |title=Treasures of the forest under threat |last=Strongman |first=Susan |date=19 June 2017 |url=https://www.rnz.co.nz/news/the-wireless/374655/treasures-of-the-forest-under-threat |archive-url=https://web.archive.org/web/20210303181004/https://www.rnz.co.nz/news/the-wireless/374655/treasures-of-the-forest-under-threat |archive-date=3 March 2021 |url-status=live |access-date=23 January 2025 |work=Radio New Zealand |issn=1179-6251}}
• {{Cite encyclopedia |title=Tall broadleaf trees — Tree rātā |encyclopedia=Te Ara: The Encyclopedia of New Zealand |last=Wassilieff |first=Maggy |url=http://www.TeAra.govt.nz/en/tall-broadleaf-trees/page-2 |archive-url=https://teara.govt.nz/en/tall-broadleaf-trees/page-2 |archive-date=22 June 2024 |url-status=live |access-date=18 December 2024 |date=24 September 2007 |page=2}}
• {{Cite encyclopedia |title=History — Māori arrival and settlement |encyclopedia=Te Ara: The Encyclopedia of New Zealand |last=Wilson |first=John |year=2005 |url=http://www.TeAra.govt.nz/en/history/page-1 |url-status=live |archive-url=https://web.archive.org/web/20240513134143/https://teara.govt.nz/en/history/page-1 |archive-date=13 May 2024|access-date=15 February 2025}}
• {{Cite web |title=Metrosideros bartlettii J.W.Dawson, New Zealand J. Bot. 23(4): 607 (1986). |url=https://www.ipni.org/n/929845-1 |url-status=live |archive-url=https://web.archive.org/web/20221204091914/https://www.ipni.org/n/929845-1 |archive-date=4 December 2022 |access-date=26 January 2025 |website=The Royal Botanic Gardens, Kew, Harvard University Herbaria & Libraries and Australian National Herbarium |year=2025 |via=the International Plant Names Index (IPNI) |ref={{sfnRef|IPNI|2025}}}}
• {{Cite news |title=Ngāti Kuri ancestral knowledge rescues endemic species from extinction |date=19 January 2024 |url=https://www.rnz.co.nz/news/te-manu-korihi/507042/ngati-kuri-ancestral-knowledge-rescues-endemic-species-from-extinction |url-status=live |archive-url=https://web.archive.org/web/20240118054622/https://www.rnz.co.nz/news/te-manu-korihi/507042/ngati-kuri-ancestral-knowledge-rescues-endemic-species-from-extinction |archive-date=18 January 2024 |access-date=9 February 2025|work=Radio New Zealand |issn=1179-6251 |ref={{sfnRef|Radio New Zealand|2024}}}}
• {{Cite web |title=New Zealand Threat Classification System {{!}} Metrosideros bartlettii J.W.Dawson |url=https://nztcs.org.nz/assessments/109706 |url-status=live |archive-url=https://web.archive.org/web/20250215044533/https://nztcs.org.nz/assessments/109706 |archive-date=15 February 2025 |access-date=15 February 2025 |website=New Zealand Threat Classification System |publisher=Department of Conservation |ref={{sfnRef|New Zealand Threat Classification System 2023}}}}

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• {{commons category-inline}}
• [https://collections.tepapa.govt.nz/object/1293570 Bartlett's rātā herbarium specimen] at the Museum of New Zealand Te Papa Tongarewa

{{New Zealand Metrosideros Species}}

{{Taxonbar|from=Q5473535}}

bartlettii

Category:Endemic flora of New Zealand

Category:Trees of New Zealand

Category:Garden plants of New Zealand

Category:Ornamental trees

Category:Endangered flora of New Zealand

Category:Taxa named by John Dawson (botanist)

Category:Plants described in 1985