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{{Short description|Species of tree endemic to New Zealand}}
{{Short description|Species of tree endemic to New Zealand}}
{{italic title}}
{{italic title}}
{{good article}}
{{Use New Zealand English|date=July 2024}}
{{Use New Zealand English|date=July 2024}}
{{Use dmy dates|date=December 2024}}
{{Use dmy dates|date=December 2024}}
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|name = Bartlett's rātā
|name = Bartlett's rātā
|image = Metrosideros bartlettii 1754747.jpg
|image = Metrosideros bartlettii 1754747.jpg
|image_caption = ''M. bartlettii'' observed by botanist [[Peter de Lange (botanist)|Peter de Lange]] in 2011
|image_caption = ''M. bartlettii'' (centre) observed by botanist [[Peter de Lange (botanist)|Peter de Lange]] in 2011
|image_alt = A New Zealand forest with Bartlett's rātā in the centre.
|image_alt = A New Zealand native forest with Bartlett's rātā (Metrosideros bartlettii_ in the centre of an image.
|status = CR
|status = CR
|status_system = IUCN3.1
|status_system = IUCN3.1
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}}
}}


'''''Metrosideros bartlettii''''', commonly known as the '''Bartlett's rātā''', is a tree endemic to only a few parts of the [[Northland Region]] in New Zealand's [[North Island]]. It is one of twelve ''[[Metrosideros]]'' species in the family [[Myrtaceae]]. The Bartlett's rātā was first discovered in 1975 by New Zealand botanist and schoolteacher, [[John Bartlett (botanist)|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 becoming [[extinct]] unless immediate [[Conservation biology|conservation]] measures are taken, due to its ongoing decline. As of 2018, only 13 adult trees are known to exist in the wild. Bartlett's rātā is common in cultivation, with it being found in several private and botanic gardens throughout New Zealand. Its current conservation status was assessed by the [[International Union for Conservation of Nature]] (IUCN) Red List as "Critically Endangered" and its population trend was assessed as "Decreasing".
'''''Metrosideros bartlettii''''', commonly known as the '''Bartlett's rātā''', is a tree [[endemism|endemic]] to only a few parts of the [[Northland Region]] in New Zealand's [[North Island]]. It is one of twelve ''[[Metrosideros]]'' species in the family [[Myrtaceae]]. The Bartlett's rātā was first discovered in 1975 by New Zealand botanist and schoolteacher, [[John Bartlett (botanist)|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 becoming [[extinct]] unless immediate [[Conservation biology|conservation]] measures are taken, due to its ongoing decline. {{as of|2018}}, only 13 adult trees are known to exist in the wild. Bartlett's rātā is common in cultivation, with it being found in several private and botanic gardens throughout New Zealand. Its current conservation status was assessed by the [[IUCN Red List]] in 2013 as "Critically Endangered" and its population trend was assessed as "Decreasing".


==Description==
==Description==
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[[File:Bartlett's rata MRD Otari.jpg|thumb|left|210px|Leafage of Bartlett's rātā (''M. bartlettii'') in [[Ōtari-Wilton's Bush]]|alt=Bright green leafage of Bartlett's rātā, in Ōtari-Wilton's Bush]]
[[File:Bartlett's rata MRD Otari.jpg|thumb|left|210px|Leafage of Bartlett's rātā (''M. bartlettii'') in [[Ōtari-Wilton's Bush]]|alt=Bright green leafage of Bartlett's rātā, 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 {{convert|25|m|abbr=on}} with a trunk up to {{convert|1|m|abbr=on}} in diameter, its [[twig]]s are often coloured dark red. Its [[Bark (botany)|bark]] is pale grey to whitish in colour. Its leaves are chartaceous to coriaceous in character, glossy, palish-green in colour and its [[Lamina (leaf)|lamina]], being 30–50 × 15–26 mm long. There are 3–4 pairs of cymules (very small flowers) on an [[inflorescence]] (flower spike) with densely spreading white hairs.{{Sfn|Dawson|1985|p=1}}
''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 {{convert|25|m|abbr=on}} with a trunk up to {{convert|1|m|abbr=on}} in diameter. Its [[twig]]s are often coloured dark red. Its [[Bark (botany)|bark]] is "papery" and pale grey to whitish in colour. The leaves are [[wikt:chartaceous|chartaceous]] to [[wikt:coriaceous|coriaceous]] in character, glossy, palish-green in colour with [[Lamina (leaf)|lamina]] being 30–50 × 15–26 mm long. There are 3–4 pairs of cymules (very small flowers) on an [[inflorescence]] (flower spike) with densely spreading white hairs.{{Sfn|Dawson|1985|p=1}}{{Sfn|Wassilieff|2007}}


Compared to other species in the [[Metrosideros]] [[genus]], flowering of the Barlett's rātā is unpredictable, making it unlikely the small wild population can regenerate without human assistance. Flowering generally occurs from October to November it produces white coloured [[Pedicel (botany)|pedicel]]s 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.{{Sfn|Dawson|1985|p=1}}{{Sfn|Bercusson|Torrence|1998|p=67}}{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|p=3}} Fruiting occurs from March to April, producing a [[hypanthium]] fruit being 2.0–2.5 × 2.5–3.0 mm long, with persistent, deflexed [[sepal]]s and 1.5–2.5 mm-long capsules. The pale orange-yellow seeds are 2.3–3.0 mm long and narrowly elliptic to narrowly oval shaped.{{Sfn|De Lange|2024}}
Compared to other species in the genus ''[[Metrosideros]]'', flowering of the Barlett's rātā is unpredictable, making it unlikely the small wild population can regenerate without human assistance. Flowering generally occurs from October to November. It produces white coloured [[Pedicel (botany)|pedicel]]s 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.{{Sfn|Dawson|1985|p=1}}{{Sfn|Bercusson|Torrence|1998|p=67}}{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|p=3}} Fruiting occurs from March to April, producing a [[hypanthium]] fruit being 2.0–2.5 × 2.5–3.0 mm long, with persistent, deflexed [[sepal]]s and 1.5–2.5 mm-long capsules. The pale orange-yellow seeds are 2.3–3.0 mm long and narrowly elliptic to narrowly oval-shaped.{{Sfn|De Lange|2024}}


===Taxonomy===
==Taxonomy==


It was first [[Discovery (observation)|discovered]] in 1975 by New Zealander [[John Bartlett (botanist)|John Bartlett]], a schoolteacher and botanist from [[Hamilton, New Zealand|Hamilton]].{{Sfn|Galloway|Edgar|1987|p=2}} Bartlet discovered the tree in Radar Bush, {{convert|9.5|km|abbr=on}} south east from [[Cape Reinga]].{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=1}}{{Sfn|Bercusson|Torrence|1998|p=67}} 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. Bartlett 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 (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]].{{Sfn|Judd|2000}} Bartlett's rātā is closely related to northern rātā;{{Sfn|De Lange|2024}} 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.{{Sfn|Dawson|1985|p=3}}
It was first [[Discovery (observation)|discovered]] in 1975 by New Zealander [[John Bartlett (botanist)|John Bartlett]], a schoolteacher and botanist from [[Hamilton, New Zealand|Hamilton]].{{Sfn|Galloway|Edgar|1987|p=2}}{{Sfn|Wassilieff|2007}} Bartlett discovered the tree in Radar Bush, {{convert|9.5|km|abbr=on}} south-east from [[Cape Reinga]].{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=1}}{{Sfn|Bercusson|Torrence|1998|p=67}} It was discovered while Bartlett was searching for [[liverworts]] in the Northland Region of New Zealand, where he found a specimen growing at the base of a large tree. Bartlett 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]]. Botanist [[John Dawson (botanist)|John Dawson]] incorrectly thought the find was [[northern rātā]] (''M. robusta''). Bartlett later returned to the area and was able to collect a branch, which he brought back to [[Wellington]].{{Sfn|Judd|2000}} Bartlett's rātā is closely related to northern rātā;{{Sfn|De Lange|2024}} its leaves are of similar size and share characteristics to [[southern rātā]] (''M. umbelata'') and northern 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.{{Sfn|Dawson|1985|p=3}}


===Etymology===
===Etymology===
The [[etymology]] of Bartlett's rātā's genus, Metrosideros, translates to English to 'iron heart'. Metrosideros derives from the [[Greek language]]; the word metra means 'core' or 'heart', and sideron means 'iron'.{{Sfn|De Lange|2024}}{{sfn|Bylsma|Clarkson|Efford|2014|p=4}} The scientifical name, ''bartlettii'', is the [[Latinisation of names|Latinisation]] after the tree's discoverer John Bartlett.{{Sfn|Dawson|1985|p=1}} Bartlett's rātā is also commonly known as rātā moehau.{{Sfn|De Lange|2024}}
The [[etymology]] of Bartlett's rātā's genus, ''Metrosideros'', translates to English to 'iron heart'. ''Metrosideros'' derives from the [[Greek language]]; 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 scientific name, ''bartlettii'', is the [[Latinisation of names|Latinisation]] after the tree's discoverer John Bartlett.{{Sfn|Dawson|1985|p=1}} Bartlett's rātā is also commonly known as rātā moehau.{{Sfn|De Lange|2024}}


<gallery mode="packed" widths="210" heights="200">
<gallery mode="packed" widths="210" heights="200">
File:Metrosideros bartlettii kz2.jpg|Close up of Bartlett's rātā's white-coloured flowers|alt=An image of Bartlett's rātā's white-coloured flowers
File:Metrosideros bartlettii kz2.jpg|Close up of Bartlett's rātā's white-coloured flowers|alt=An image of Bartlett's rātā's blooming white-coloured flowers
File:Metrosideros bartlettii bark.jpg|"Flakey" bark of Bartlett's rātā|alt=The "flakey" grey to whitish bark of Bartlett's rātā
File:Metrosideros bartlettii bark.jpg|"Papery" bark of Bartlett's rātā|alt=The "Papery" grey to whitish coloured bark of Bartlett's rātā
File:Metrosideros bartlettii.jpg|Recently formed [[bud]]s of the tree|alt=Recently formed buds of Bartlett's rātā
File:Metrosideros bartlettii.jpg|Recently formed [[bud]]s of the tree|alt=Recently formed buds of Bartlett's rātā
</gallery>
</gallery>


==Ecology==
==Ecology==
Bartlett's ratā is often observed to be utilised by birds and insects (such as [[bee]]s and [[flies]]), which may help spread pollen from other ''Metrosideros'' species.{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|p=8}}{{Sfn|Lehnebach|Van der Walt|2018|p=3}} New Zealand species of ''Metrosideros'' are pollinated by nectar-feeding birds, such as the [[tūī]] (''Prosthemadera novaeseelandiae'') which are known to forage over distances of {{convert|15|km|abbr=on}}.{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=8}} Wind and rain may cause self-pollination but the likelihood of producing viable seeds is low or non-existent. A 2022 study by the ''[[Pacific Conservation Biology]]'' revealed [[cross-pollination]] is the only method that produces viable Barlett's rātā seeds that can be utilised in other augmented wild populations.{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|p=8}}{{sfn|Van der Walt|Alderton-Moss|Lehnebach|2022|p=2}}


A 2021 study by the ''[[New Zealand Journal of Botany]]'' conducted scientific analyses of Bartlett's rātā at [[Ōtari-Wilton's Bush]] (in Wellington). The study confirmed the [[self-incompatibility]] of Bartlett's rātā; individuals depend on pollen from unrelated individuals to fruit. Recent and historical genetic research has confirmed [[Hybrid (biology)|hybridisation]] and [[introgression]] are possible between closely related species in the genus ''Metrosideros''. The average [[germination]] of the seeds from hand pollination in this study was low, which is consistent with other species in the family [[Myrtaceae]], such as [[pōhutukawa]] (''Metrosideros excelsa'') and [[mānuka]] (''Leptospermum scoparium'').{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|p=14}}
Bartlett's ratā is often observered to be utilised by birds and insects (such as [[bee]]s and [[flies]]), which may help spread pollen from other Metrosideros species.{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|p=8}}{{Sfn|Lehnebach|Van der Walt|2018|p=3}} New Zealand species of Metrosideros are pollinated by nectar-feeding birds, such as the [[tūī]] (''Prosthemadera novaeseelandiae'') which are known to forage over distances of {{convert|15|km|abbr=on}}.{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=8}} Wind and rain may cause self-pollination but the likelihood of producing viable seeds is low or nonexistent. A 2022 study by the ''[[Pacific Conservation Biology]]'' revealed [[cross-pollination]] is the only method that produces viable Barlett's rātā seeds that can be utilised in other augmented wild populations.{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|p=8}}{{sfn|Van der Walt|Alderton-Moss|Lehnebach|2022|p=2}}

A 2021 study by the ''[[New Zealand Journal of Botany]]'' conducted scintifical analyses of Bartlett's rātā at [[Ōtari-Wilton's Bush]] (in [[Wellington]]) which confirmed the [[self-incompatibility]] of Bartlett's rātā individuals depend on pollen from unrelated individuals to set its fruit. Recent and historical genetical research has confirmed [[Hybrid (biology)|hybridisation]] and [[introgression]] are possible between closely related species in the Metrosideros genus. The average [[germination]] of the seeds from Bartlett's rātā's controlled pollination in this study, was usually low, which is consistent with other species in the family [[Myrtaceae]], such as [[pōhutukawa]] (''Metrosideros excelsa'') and [[mānuka]] (''Leptospermum scoparium'').{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|p=14}}


==Distribution==
==Distribution==


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.{{Sfn|De Lange|2024}}{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=8}} It is usually found growing near bodies of water (such as streams) and in swamplands.{{Sfn|Dawson|1985|p=2}} An article from ''[[Molecular Ecology (journal)|Molecular Ecology]]'', published in 2000, documented 31 adult trees.{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=1}} A 2018 study by the ''[[New Zealand Journal of Botany]]'' has since documented only 13 adult trees,{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|pp=2–3}}{{Sfn|Lehnebach|Van der Walt|2018|pp=2–3}} and most of these trees are located on private land.{{Sfn|Stowell|2017}} Bartlett's rātā was likely never a common tree. A number of surveys conducted in the 1990s revealed individuals were only present in three populations.{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|p=1}}
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.{{Sfn|De Lange|2024}}{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=8}} It is usually found growing near bodies of water (such as streams) and in swamplands.{{Sfn|Dawson|1985|p=2}} An article from ''[[Molecular Ecology (journal)|Molecular Ecology]]'', published in 2000, documented 31 adult trees.{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=1}} A 2018 study by the ''New Zealand Journal of Botany'' has since documented only 13 adult trees,{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|pp=2–3}}{{Sfn|Lehnebach|Van der Walt|2018|pp=2–3}} and most of these trees are located on private land.{{Sfn|Stowell|2017}} Bartlett's rātā was likely never a common tree. A number of surveys conducted in the 1990s revealed individuals were only present in three populations.{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|p=1}}


==Conservation==
==Conservation==
[[File:Common Brushtail Possum - Flickr - GregTheBusker (1).jpg|210px|thumb|right|Bartlett's rātā historical decline is largely due to land use changes following settlement, and the introduction of [[common brushtail possums|bushtail possums]].|alt=An image of a common bush tail possum. Bartlett's rātā's decline is largely due to their introduction into New Zealand.]]
[[File:Common Brushtail Possum - Flickr - GregTheBusker (1).jpg|210px|thumb|right|Bartlett's rātā historical decline is largely due to land use changes following settlement, and the introduction of [[common brushtail possums|brushtail possums]].|alt=An image of a common bush tail possum. Bartlett's rātā's decline is largely due to their introduction into New Zealand.]]
Its current conservation status was assessed by the [[IUCN Red List]] in 2013 as "Critically Endangered" and its population trend was assessed as "Decreasing".{{Sfn|De Lange|2014}} The historical decline of Bartlett's rātā is largely due to land use changes following settlement, and the introduction of [[Common brushtail possum in New Zealand|brushtail possums]] (an invasive species in New Zealand).{{sfn|Van der Walt|Alderton-Moss|Lehnebach|2022|p=2}}{{sfn|Pattabiraman|Morgan-Richards|Powlesland|Trewick|2022|p=3}} Although Bartlett's rātā is uncommon in the wild, it is common in cultivation, with it being found in several private and botanic gardens throughout the country (such as Ōtari-Wilton's Bush).{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|pp=2–3}}{{Sfn|Lehnebach|Van der Walt|2018}}
Its current conservation status was assessed by the [[IUCN Red List]] in 2013 as "Critically Endangered" and its population trend was assessed as "Decreasing".{{Sfn|De Lange|2014}} The historical decline of Bartlett's rātā is largely due to land use changes following settlement, and the introduction of [[Common brushtail possum in New Zealand|brushtail possums]] (an invasive species in New Zealand).{{sfn|Van der Walt|Alderton-Moss|Lehnebach|2022|p=2}}{{sfn|Pattabiraman|Morgan-Richards|Powlesland|Trewick|2022|p=3}} Although Bartlett's rātā is uncommon in the wild, it is common in cultivation, with it being found in several private and botanic gardens throughout the country (such as Ōtari-Wilton's Bush).{{sfn|Nadarajan|van der Walt|Lehnebach|Saeiahagh|2021|pp=2–3}}{{Sfn|Lehnebach|Van der Walt|2018}}


Bartlett's rātā [[Habitat destruction|habitat disturbance]] began with the arrival of the [[Polynesians|Polynesian]] settlers. Many forests were later cleared when the European ([[Pākehā]]) settlers arrived later, starting in the early 1800s. Its habitat retreated into the steeper valleys, especially those under intense fire shadows. It was not until the late 1960s that the far north's native forest area began to decline. Although the forests in Northland are gradually recovering, the population of Bartlett's rātā remains low and widely scattered.{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=8}}
Bartlett's rātā [[Habitat destruction|habitat disturbance]] began with the arrival of the [[Polynesians|Polynesian]] settlers. Many forests were later cleared when the European ([[Pākehā]]) settlers arrived later, starting in the early 1800s. Its habitat retreated into the steeper valleys, especially those under intense fire shadows. It was not until the late 1960s that the far north's native forest area began to decline. Although the forests in Northland are gradually recovering, the population of Bartlett's rātā remains low and widely scattered.{{sfn|Drummond|Keeling|Richardson|Gardner|2000|p=8}}


Bartlett's rātā has a high chance of becoming [[extinct]], unless immediate conservation measures are taken, due to its ongoing decline, population size, and reproductive failure. Bartlett's rātā breeding strategy favours [[cross-pollination]], and has little inbreeding. Bartlett's rātā under cultivation has low levels of genetic variety, which might restrict its ability to contribute to the its overall conservation.{{sfn|Van der Walt|Alderton-Moss|Lehnebach|2022|p=9}}
Bartlett's rātā has a high chance of becoming [[extinct]] unless immediate [[Conservation biology|conservation]] measures are taken, due to its ongoing decline, small population size, and reproductive failure. Bartlett's rātā breeding strategy favours cross-pollination, and has little [[inbreeding]]. Bartlett's rātā under cultivation has low levels of genetic variety, which might restrict its ability to contribute to its overall conservation.{{sfn|Van der Walt|Alderton-Moss|Lehnebach|2022|p=9}}


==See also==
==See also==
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* {{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 |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=10.1080/0028825X.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 |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)|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 (journal)|Molecular Ecology]]|volume=9|issue=8|pages=1149–1157|pmid=10964234|s2cid=20499423|doi-access=free}}
* {{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)|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 (journal)|Molecular Ecology]]|volume=9|issue=8|pages=1149–1157|pmid=10964234|s2cid=20499423|doi-access=free}}
* {{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=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|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=1 November 2018|doi=10.1080/0028825X.1987.10409963}}
* {{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|doi=10.1080/0028825X.1987.10409963 |doi-access=free}}
* {{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 |pages=72–89}}
* {{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 |url-access=subscription |pages=72–89}}
* {{cite journal |last=Pattabiraman |first=Nimeshika |last2=Morgan-Richards |first2=Mary |last3=Powlesland |first3=Ralph |last4=Trewick |first4=Steven A. |title=Unrestricted gene flow between two subspecies of translocated brushtail possums (Trichosurus vulpecula) in Aotearoa New Zealand |journal=Biological Invasions |volume=24 |issue=1 |date=2022 |issn=1387-3547 |doi=10.1007/s10530-021-02635-z |doi-access=free |pages=247–260 |url=https://link.springer.com/content/pdf/10.1007/s10530-021-02635-z.pdf |access-date=17 December 2024}}
* {{cite journal |last=Pattabiraman |first=Nimeshika |last2=Morgan-Richards |first2=Mary |last3=Powlesland |first3=Ralph |last4=Trewick |first4=Steven A. |title=Unrestricted gene flow between two subspecies of translocated brushtail possums (''Trichosurus vulpecula'') in Aotearoa New Zealand |journal=Biological Invasions |volume=24 |issue=1 |date=2022 |issn=1387-3547 |doi=10.1007/s10530-021-02635-z |doi-access=free |pages=247–260 |url=https://link.springer.com/content/pdf/10.1007/s10530-021-02635-z.pdf |access-date=17 December 2024}}
* {{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 |journal=[[New Zealand Journal of Botany]] |volume=52 |issue=3 |date=3 July 2014 |issn=0028-825X |doi=10.1080/0028825X.2014.926278 |pages=365–385}}
* {{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 |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. |journal=[[New Zealand Plant Conservation Network]] |url=https://www.nzpcn.org.nz/site/assets/files/0/51/296/trilepidea-172-180331.pdf |last=Lehnebach |first=C. A. |volume=172 |pages=2-3 |last2=Van der Walt |first2=K. |year=2018}}
* {{Cite journal |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. |journal=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=C. A. |volume=172 |pages=2–3 |last2=Van der Walt |first2=K. |year=2018 |via=[[New Zealand Plant Conservation Network]]}}
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* {{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|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=live |last=De Lange |first=Peter |access-date=2024-12-17 |website=[[New Zealand Plant Conservation Network]] |year=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=live |last=De Lange |first=Peter |access-date=2024-12-17 |website=[[New Zealand Plant Conservation Network]] |year=2024}}
* {{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/ |archive-date=3 March 2024 |url-status=live|access-date=2024-12-17 |work=[[New Zealand Geographic]] |year=2000 |issue=47}}
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Revision as of 16:31, 27 December 2024

Bartlett's rātā
A New Zealand native forest with Bartlett's rātā (Metrosideros bartlettii_ in the centre of an image.
M. bartlettii (centre) 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 a tree endemic to only a few parts of the Northland Region in New Zealand's North Island. It is one of twelve Metrosideros species in the family Myrtaceae. The 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 becoming extinct unless immediate conservation measures are taken, due to its ongoing decline. As of 2018, only 13 adult trees are known to exist in the wild. Bartlett's rātā is common in cultivation, with it being found in several private and botanic gardens throughout New Zealand. Its current conservation status was assessed by the IUCN Red List in 2013 as "Critically Endangered" and its population trend was assessed as "Decreasing".

Description

Bright green leafage of Bartlett's rātā, in Ōtari-Wilton's Bush
Leafage 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. Its twigs are often coloured dark red. Its bark is "papery" and pale grey to whitish in colour. The leaves are chartaceous to coriaceous in character, glossy, palish-green in colour with lamina being 30–50 × 15–26 mm long. There are 3–4 pairs of cymules (very small flowers) on an inflorescence (flower spike) with densely spreading white hairs.[2][3]

Compared to other species in the genus Metrosideros, flowering of the Barlett's rātā is unpredictable, making it unlikely the small wild population can regenerate without human assistance. Flowering generally occurs from October to November. It produces white coloured 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][4][5] Fruiting occurs from March to April, producing a hypanthium fruit being 2.0–2.5 × 2.5–3.0 mm long, with persistent, deflexed sepals and 1.5–2.5 mm-long capsules. The pale orange-yellow seeds are 2.3–3.0 mm long and narrowly elliptic to narrowly oval-shaped.[6]

Taxonomy

It was first discovered in 1975 by New Zealander John Bartlett, a schoolteacher and botanist from Hamilton.[7][3] Bartlett discovered the tree in Radar Bush, 9.5 km (5.9 mi) south-east from Cape Reinga.[8][4] It was discovered while Bartlett was searching for liverworts in the Northland Region of New Zealand, where he found a specimen growing at the base of a large tree. Bartlett 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. Botanist John Dawson incorrectly thought the find was northern rātā (M. robusta). Bartlett later returned to the area and was able to collect a branch, which he brought back to Wellington.[9] Bartlett's rātā is closely related to northern rātā;[6] its leaves are of similar size and share characteristics to southern rātā (M. umbelata) and northern 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.[10]

Etymology

The etymology of Bartlett's rātā's genus, Metrosideros, translates to English to 'iron heart'. Metrosideros derives from the Greek language; the word metra means 'core' or 'heart', and sideron means 'iron'.[6][11] The scientific name, bartlettii, is the Latinisation after the tree's discoverer John Bartlett.[2] Bartlett's rātā is also commonly known as rātā moehau.[6]

Ecology

Bartlett's ratā is often observed to be utilised by birds and insects (such as bees and flies), which may help spread pollen from other Metrosideros species.[12][13] New Zealand species of Metrosideros are pollinated by nectar-feeding birds, such as the tūī (Prosthemadera novaeseelandiae) which are known to forage over distances of 15 km (9.3 mi).[14] Wind and rain may cause self-pollination but the likelihood of producing viable seeds is low or non-existent. A 2022 study by the Pacific Conservation Biology revealed cross-pollination is the only method that produces viable Barlett's rātā seeds that can be utilised in other augmented wild populations.[12][15]

A 2021 study by the New Zealand Journal of Botany conducted scientific analyses of Bartlett's rātā at Ōtari-Wilton's Bush (in Wellington). The study confirmed the self-incompatibility of Bartlett's rātā; individuals depend on pollen from unrelated individuals to fruit. Recent and historical genetic research has confirmed hybridisation and introgression are possible between closely related species in the genus Metrosideros. The average germination of the seeds from hand pollination in this study was low, which is consistent with other species in the family Myrtaceae, such as pōhutukawa (Metrosideros excelsa) and mānuka (Leptospermum scoparium).[16]

Distribution

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.[6][14] It is usually found growing near bodies of water (such as streams) and in swamplands.[17] An article from Molecular Ecology, published in 2000, documented 31 adult trees.[8] A 2018 study by the New Zealand Journal of Botany has since documented only 13 adult trees,[18][19] and most of these trees are located on private land.[20] Bartlett's rātā was likely never a common tree. A number of surveys conducted in the 1990s revealed individuals were only present in three populations.[21]

Conservation

An image of a common bush tail possum. Bartlett's rātā's decline is largely due to their introduction into New Zealand.
Bartlett's rātā historical decline is largely due to land use changes following settlement, and the introduction of brushtail possums.

Its current conservation status was assessed by the IUCN Red List in 2013 as "Critically Endangered" and its population trend was assessed as "Decreasing".[1] The historical decline of Bartlett's rātā is largely due to land use changes following settlement, and the introduction of brushtail possums (an invasive species in New Zealand).[15][22] Although Bartlett's rātā is uncommon in the wild, it is common in cultivation, with it being found in several private and botanic gardens throughout the country (such as Ōtari-Wilton's Bush).[18][23]

Bartlett's rātā habitat disturbance began with the arrival of the Polynesian settlers. Many forests were later cleared when the European (Pākehā) settlers arrived later, starting in the early 1800s. Its habitat retreated into the steeper valleys, especially those under intense fire shadows. It was not until the late 1960s that the far north's native forest area began to decline. Although the forests in Northland are gradually recovering, the population of Bartlett's rātā remains low and widely scattered.[14]

Bartlett's rātā has a high chance of becoming extinct unless immediate conservation measures are taken, due to its ongoing decline, small population size, and reproductive failure. Bartlett's rātā breeding strategy favours cross-pollination, and has little inbreeding. Bartlett's rātā under cultivation has low levels of genetic variety, which might restrict its ability to contribute to its overall conservation.[24]

See also

References

Citations

Works cited

Journals

Miscellaneous