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Silver fern
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Silver fern
Alsophila dealbata (synonyms Alsophila tricolor and Cyathea dealbata), commonly known as the silver fern or silver tree-fern, or as ponga /ˈpɒŋə/ or punga /ˈpʌŋə/ (from Māori kaponga or ponga), is a species of medium-sized tree fern, endemic to New Zealand. The fern is usually recognisable by the silver-white colour of the under-surface of mature fronds. It is a symbol commonly associated with the country both overseas and by New Zealanders themselves.
This fern is known to grow to heights of 10 metres (33 ft) or more (though it occasionally takes a rare creeping form). The crown is dense, and mature fronds can be as much as 3 metres (9.8 ft) long and 1 m (3 ft 3 in) wide with a silver-white colouration on the undersides. The fronds may be bipinnately compound or tripinnate. The underside colouration is less intensely silvery or patchy in younger plants and juveniles are pale green. This distinctive silver colouration has made them useful for laying along tracks for night walking. The scales are a dark brown and are often twisted and glossy. Rhizomes very rarely prostrate, usually erect, forming a woody trunk up to 12 metres (39 ft) tall, 160 to 450 millimetres (6.3 to 17.7 in) in diameter, covered in light brown or white projecting stipe bases, bearing scales near the apex.
The species was first formally described in 1786 by German naturalist Georg Forster in the book Florulae Insularum Australium Prodromus, who used the name Polypodium dealbatum. The species was moved to the genus Cyathea by Olof Swartz in 1801, leading to the scientific name Cyathea dealbata. The species was moved to the genus Alsophila in 1970 by Rolla M. Tryon Jr., who used the name Alsophila tricolor, citing William Colenso's 1883 description of Cyathea tricolor, which Colenso believed was a species distinct from Cyathea dealbata.
The current preferred scientific name is disputed, with Plants of the World Online, New Zealand Plant Conservation Network, and the Synonymic Checklist and Distribution of Ferns and Lycophytes of the World Version 25.06 preferring Alsophila dealbata, Manaaki Whenua – Landcare Research preferring Cyathea dealbata and World Flora Online preferring Alsophila tricolor. The name Alsophila tricolor was considered the correct scientific name for the species, due to the species epithet dealbata being preoccupied in the genus by a species described in 1848 by Carl Borivoj Presl, now considered a synonym of Sphaeropteris glauca. In 2025 it was shown that the silver fern has priority to use this name over the species Presl described, due to a reference made by August Carl Joseph Corda to the species in 1838, making Presl's use an illegitimate later homonym.
The species epithet dealbata means whitish, and refers to the underside of the fronds. The Māori word ponga, pronounced [ˈpɔŋa], is a term used across Polynesian languages to describe tree ferns, such as Sphaeropteris lunulata in Tongan and Samoan or Angiopteris evecta in Samoan. It has been borrowed into New Zealand English using both the spelling ponga and punga, and is used as a generic term for tree ferns, and to refer to tree fern logs when used for landscaping purposes.[citation needed] English speakers generally pronounce the word /ˈpʌŋə/ PUNG-ə.[citation needed] Other Māori language names for the plant include kaponga, kātote, or poka in southern dialects.
Arriving relatively late in New Zealand's history during the Pliocene epoch (around 5.0–1.8 million years ago), the silver fern occurs on the main islands of New Zealand—although absent from the west and south regions of the South Island, on the Chatham Islands to the east, and is also native to Lord Howe Island. It has also become naturalised in Ireland. Its primary habitat is subcanopy areas of drier forests and in open scrub, although it is occasionally found on bush margins and in more open areas, and has been recorded from amongst rushes in a dune slack.
The fern is known to grow well in well-drained humus, and once established, it will tolerate drier conditions. It does best when sheltered from winds and should be protected from frost. Evidence of large amount of macro-charcoals in the top layers of soil suggest that Alsophila tricolor establishes itself in areas where anthropogenic fires occur.
In traditional Māori culture, ponga is seen as a symbol new life and growth. Ponga trunks were often used in the construction of whare, walls and palisades. The koru symbol, which depicts the shape of an unfurling silver fern frond, is found extensively in Māori art, including in designs of carvings, marae and tā moko, Pūrākau (traditional stories) involve the silver fern once living in the sea, and that hunters at night time would use the white underside of fern fronds to mark a path home in the darkness, as the undersides could easily catch moonlight.
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Silver fern
Alsophila dealbata (synonyms Alsophila tricolor and Cyathea dealbata), commonly known as the silver fern or silver tree-fern, or as ponga /ˈpɒŋə/ or punga /ˈpʌŋə/ (from Māori kaponga or ponga), is a species of medium-sized tree fern, endemic to New Zealand. The fern is usually recognisable by the silver-white colour of the under-surface of mature fronds. It is a symbol commonly associated with the country both overseas and by New Zealanders themselves.
This fern is known to grow to heights of 10 metres (33 ft) or more (though it occasionally takes a rare creeping form). The crown is dense, and mature fronds can be as much as 3 metres (9.8 ft) long and 1 m (3 ft 3 in) wide with a silver-white colouration on the undersides. The fronds may be bipinnately compound or tripinnate. The underside colouration is less intensely silvery or patchy in younger plants and juveniles are pale green. This distinctive silver colouration has made them useful for laying along tracks for night walking. The scales are a dark brown and are often twisted and glossy. Rhizomes very rarely prostrate, usually erect, forming a woody trunk up to 12 metres (39 ft) tall, 160 to 450 millimetres (6.3 to 17.7 in) in diameter, covered in light brown or white projecting stipe bases, bearing scales near the apex.
The species was first formally described in 1786 by German naturalist Georg Forster in the book Florulae Insularum Australium Prodromus, who used the name Polypodium dealbatum. The species was moved to the genus Cyathea by Olof Swartz in 1801, leading to the scientific name Cyathea dealbata. The species was moved to the genus Alsophila in 1970 by Rolla M. Tryon Jr., who used the name Alsophila tricolor, citing William Colenso's 1883 description of Cyathea tricolor, which Colenso believed was a species distinct from Cyathea dealbata.
The current preferred scientific name is disputed, with Plants of the World Online, New Zealand Plant Conservation Network, and the Synonymic Checklist and Distribution of Ferns and Lycophytes of the World Version 25.06 preferring Alsophila dealbata, Manaaki Whenua – Landcare Research preferring Cyathea dealbata and World Flora Online preferring Alsophila tricolor. The name Alsophila tricolor was considered the correct scientific name for the species, due to the species epithet dealbata being preoccupied in the genus by a species described in 1848 by Carl Borivoj Presl, now considered a synonym of Sphaeropteris glauca. In 2025 it was shown that the silver fern has priority to use this name over the species Presl described, due to a reference made by August Carl Joseph Corda to the species in 1838, making Presl's use an illegitimate later homonym.
The species epithet dealbata means whitish, and refers to the underside of the fronds. The Māori word ponga, pronounced [ˈpɔŋa], is a term used across Polynesian languages to describe tree ferns, such as Sphaeropteris lunulata in Tongan and Samoan or Angiopteris evecta in Samoan. It has been borrowed into New Zealand English using both the spelling ponga and punga, and is used as a generic term for tree ferns, and to refer to tree fern logs when used for landscaping purposes.[citation needed] English speakers generally pronounce the word /ˈpʌŋə/ PUNG-ə.[citation needed] Other Māori language names for the plant include kaponga, kātote, or poka in southern dialects.
Arriving relatively late in New Zealand's history during the Pliocene epoch (around 5.0–1.8 million years ago), the silver fern occurs on the main islands of New Zealand—although absent from the west and south regions of the South Island, on the Chatham Islands to the east, and is also native to Lord Howe Island. It has also become naturalised in Ireland. Its primary habitat is subcanopy areas of drier forests and in open scrub, although it is occasionally found on bush margins and in more open areas, and has been recorded from amongst rushes in a dune slack.
The fern is known to grow well in well-drained humus, and once established, it will tolerate drier conditions. It does best when sheltered from winds and should be protected from frost. Evidence of large amount of macro-charcoals in the top layers of soil suggest that Alsophila tricolor establishes itself in areas where anthropogenic fires occur.
In traditional Māori culture, ponga is seen as a symbol new life and growth. Ponga trunks were often used in the construction of whare, walls and palisades. The koru symbol, which depicts the shape of an unfurling silver fern frond, is found extensively in Māori art, including in designs of carvings, marae and tā moko, Pūrākau (traditional stories) involve the silver fern once living in the sea, and that hunters at night time would use the white underside of fern fronds to mark a path home in the darkness, as the undersides could easily catch moonlight.
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