''Sphaeropteris medullaris'',

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

''Cyathea medullaris'', commonly known as mamaku or black tree fern, is a large

tree fern Tree ferns are arborescent (tree-like) ferns that grow with a trunk (botany), trunk elevating the fronds above ground level, making them trees. Many extant tree ferns are members of the order Cyatheales, to which belong the families Cyatheaceae ( ...

up to tall. It is distributed across the south-west Pacific from

Fiji Fiji, officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists of an archipelago of more than 330 islands—of which about ...

to Pitcairn Island and is a common plant found in forests of New Zealand.

Description

The trunk is black and covered with distinctive hexagonal stipe bases. The

frond A frond is a large, divided leaf. In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group. Other botanists allow the term frond to also apply to the lar ...

s may be up to long, and arch upwards from the crown. Dead fronds are shed except in very young plants. The primary pinnae are from to long, and the undersides have scales with spines along their margins. As many as 40,000 leaflets have been counted on a single frond. The stipes are thick, black, very rough to the touch, and are similarly covered in black scales with marginal spines. ''Sphaeropteris medullaris'' can be readily distinguished from related species by the hexagonal stipe scars on the trunk, and by the scales with spines on their margins. Fully grown trees can reach a height of , making the species the tallest tree fern found in New Zealand. ''Sphaeropteris medullaris'' is one of the fastest growing tree ferns alongside '' Sphaeropteris excelsa'', with both species growing as much as a year. The tree produces a red

mucilage Mucilage is a thick gluey substance produced by nearly all plants and some microorganisms. These microorganisms include protists which use it for their locomotion, with the direction of their movement always opposite to that of the secretion of ...

when the trunk is cut, which is a Non-Newtonian fluid.

Taxonomy and etymology

The species was first described by German botanist Johann Jakob Bernhardi in 1801 as ''Sphaeropteris medullaris''. The species epithet ''medullaris'' means

pith Pith, or medulla, is a tissue in the stems of vascular plants. Pith is composed of soft, spongy parenchyma cells, which in some cases can store starch. In eudicotyledons, pith is located in the center of the stem. In monocotyledons, it ex ...

y, referring to the white, edible substance found on the inside of the tree fern's trunk. Sources variously refer to the species as ''Sphaeropteris medullaris'' or ''Cyathea medullaris''. ''

Sphaeropteris ''Sphaeropteris'' is a genus of tree ferns in the family Cyatheaceae. It has been treated as a subgenus within the genus ''Cyathea'', but is accepted in the Pteridophyte Phylogeny Group classification of 2016 (PPG I). Description Species of ' ...

'' is a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

within the family

Cyatheaceae The Cyatheaceae are a family of ferns, the scaly tree ferns, one of eight families in the order Cyatheales in the Pteridophyte Phylogeny Group classification of 2016 (PPG I). Alternatively, the family may defined much more broadly (Cyatheaceae ...

. While some sources prefer a broader definition of the genus '' Cyathea'' and treats ''Sphaeropteris'' as a sub-genus, the

Pteridophyte Phylogeny Group The Pteridophyte Phylogeny Group (PPG) is an informal international group of systematic botanists who collaborate to establish on the classification of pteridophytes ( lycophytes and ferns) that reflects knowledge about plant relationships discove ...

classification of 2016 (PPG I) treats ''Sphaeropteris'' as a genus separate to ''Cyathea''. The species is referred to as mamaku or mamau in several

Polynesian languages The Polynesian languages form a genealogical group of languages, itself part of the Oceanic branch of the Austronesian family. There are 38 Polynesian languages, representing 7 percent of the 522 Oceanic languages, and 3 percent of the Austr ...

, including

Māori Māori or Maori can refer to: Relating to the Māori people * Māori people of New Zealand, or members of that group * Māori language, the language of the Māori people of New Zealand * Māori culture * Cook Islanders, the Māori people of the Co ...

. Early European settlers to New Zealand referred to the species as black tree fern, or as black mamaku. Other

names include katātā, kōrau, and pītau.

Distribution

The species is found across many southwestern

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

islands, including

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

, the

Marquesas Islands The Marquesas Islands ( ; or ' or ' ; Marquesan language, Marquesan: ' (North Marquesan language, North Marquesan) and ' (South Marquesan language, South Marquesan), both meaning "the land of men") are a group of volcano, volcanic islands in ...

Tahiti Tahiti (; Tahitian language, Tahitian , ; ) is the largest island of the Windward Islands (Society Islands), Windward group of the Society Islands in French Polynesia, an overseas collectivity of France. It is located in the central part of t ...

, the

Austral Islands The Austral Islands ( officially ''Archipel des Australes;'' ) are the southernmost group of islands in French Polynesia, an overseas country of France, overseas country of the France, French Republic in the Oceania, South Pacific. Geographicall ...

, and Pitcairn Island. It is not present in the

Kermadec Islands The Kermadec Islands ( ; ) are a subtropical island arc in the South Pacific Ocean northeast of New Zealand's North Island, and a similar distance southwest of Tonga. The islands are part of New Zealand. They are in total area and uninhabit ...

. ''Sphaeropteris medullaris'' is common in lowland forest throughout the

North Island The North Island ( , 'the fish of Māui', historically New Ulster) is one of the two main islands of New Zealand, islands of New Zealand, separated from the larger but less populous South Island by Cook Strait. With an area of , it is the List ...

of New Zealand. In the

South Island The South Island ( , 'the waters of Pounamu, Greenstone') is the largest of the three major islands of New Zealand by surface area, the others being the smaller but more populous North Island and Stewart Island. It is bordered to the north by ...

, its distribution is more localised. It is fairly common in wetter coastal areas, but rare in the drier eastern parts and absent in

Canterbury Canterbury (, ) is a City status in the United Kingdom, city and UNESCO World Heritage Site, in the county of Kent, England; it was a county borough until 1974. It lies on the River Stour, Kent, River Stour. The city has a mild oceanic climat ...

and

Otago Otago (, ; ) is a regions of New Zealand, region of New Zealand located in the southern half of the South Island and administered by the Otago Regional Council. It has an area of approximately , making it the country's second largest local go ...

. In New Zealand it also occurs on the

Three Kings Islands 3 (three) is a number, numeral (linguistics), numeral and numerical digit, digit. It is the natural number following 2 and preceding 4, and is the smallest odd prime number and the only prime preceding a square number. It has religious and cul ...

in the far north, on

Stewart Island / Rakiura Stewart Island (, 'Aurora, glowing skies', officially Stewart Island / Rakiura, formerly New Leinster) is New Zealand's third-largest island, located south of the South Island, across Foveaux Strait. It is a roughly triangular island wit ...

in the far south and in the

Chatham Islands The Chatham Islands ( ; Moriori language, Moriori: , 'Misty Sun'; ) are an archipelago in the Pacific Ocean about east of New Zealand's South Island, administered as part of New Zealand, and consisting of about 10 islands within an approxima ...

Ecology

''Sphaeropteris medullaris'' is a coloniser of disturbed hillside areas in many high humidity forests of New Zealand, a role taken by mānuka and

kānuka ''Kunzea ericoides'', commonly known as kānuka or white tea-tree, is a tree or shrub in the myrtle Family (biology), family, Myrtaceae and is endemic to New Zealand. It has white or pink flowers similar to those of ''Leptospermum'' and from its ...

in many areas of New Zealand. It is likely that mānuka and kānuka only recently became more likely to establish disturbed soil, since the arrival of people to New Zealand, and the impact of fires on native forests.

Cultivation

''Sphaeropteris medullaris'' will grow from fresh spores, but this is slow. Plants are easy to transplant when they are young. It is also possible to plant newly felled trunks which will generally sprout again, provided they are watered with care. They are hardy in various conditions once established. It has gained the

Royal Horticultural Society The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity. The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr ...

Award of Garden Merit The Award of Garden Merit (AGM) is a long-established award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. It includes the full range of cultivated p ...

as an ornamental.

Uses and traditional culture

In traditional

Māori culture Māori culture () is the customs, cultural practices, and beliefs of the Māori people of New Zealand. It originated from, and is still part of, Polynesians, Eastern Polynesian culture. Māori culture forms a distinctive part of Culture of New ...

, the drooping fronds of ''Sphaeropteris medullaris'' is associated with grief and sorrow. Traditional stories describe Mamaku and Toroa (the albatross) as human lovers who would argue and bicker. Their arguing angered the gods, who turned Toroa into an albatross, and Mamaku into a tree fern. The 1889 book ''The Useful Native Plants of Australia'' records that Indigenous Australians ate the pith of this fern tree which contained a certain amount of starch similar to sago. The plant is also a traditional food source in New Zealand, where both the pith and coiled fern fronds are used. Traditionally, ''Sphaeropteris medullaris'' was seen as a food for difficult times, as harvesting the pith will typically kill the tree. The bark is used to create a

taonga pūoro Taonga pūoro are the traditional musical instruments of the Māori people of New Zealand. The instruments previously fulfilled many functions within Māori society including a call to arms, dawning of the new day, communications with the gods ...

(traditional Māori instrument) called rōria. Tree fern trunks, including those of ''S. medullaris'', have been used as rough building material and also for makeshift trackwork.

Gallery

Cyathea medullaris.jpg, The black trunk with characteristic hexagonal stipe bases seen here from this specimen from RBGE, Edinburgh Cyathea-med2.jpg, Luxuriant groups are a common sight in the New Zealand forest. fiddlehead black tree fern.jpg, The expanding frond forms a fiddlehead or koru Cyathea medullaris (G.Forst.) Sw. (AM AK274337).jpg, Herbarium specimen of ''Sphaeropteris medullaris''