| Dacrydium cupressinum | |
|---|---|
_(cropped_ver_2).jpg) | |
| A matureD. cupressinum specimen in the South Island'sWest Coast Region | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Gymnospermae |
| Division: | Pinophyta |
| Class: | Pinopsida |
| Order: | Araucariales |
| Family: | Podocarpaceae |
| Genus: | Dacrydium |
| Species: | D. cupressinum |
| Binomial name | |
| Dacrydium cupressinum | |
| Synonyms[2] | |
Dacrydium cupressinum, commonly known asrimu, is an evergreen conifernative to New Zealand. A member of thePodocarpaceae, the tree usually reaches 35 metres (100 feet) in height, but may reach up to 60 metres (200 feet) and can have a stouttrunk up to 2 m (6 ft 7 in) in diameter. It isdioecious, meaning individual trees are either male or female. Rimu is the country's most common native conifer, itsrange covers theNorth,South, andStewart Islands. Rimu has an estimated lifespan of 600–800 years, although it may live as long as 1,200 years.
The nameD. cupressinum was first publishedinvalidly in 1786 byDaniel Solander andGeorg Forster. However the species was first given a valid description in 1806 byAylmer Lambert. Thesecond part of the scientific name,cupressinum, was given because of the tree's similarity withcypress species. Rimu's fruits are consumed by various birds such asbellbirds,kererū, and thetūī. Rimu's fruits also provide an important source of food and vitamins for the native flightless parrot, thekākāpō, which will onlymate during years of heavy fruiting. Many different plants grow on the tree's trunk and branches, using it for support, which are calledepiphytes andhemi-epiphytes. Rimu also playshost to numerous insect species.
InMāori culture,D. cupressinum is of great importance. Rimu had severalmedicinal purposes forMāori, and the British missionary,Richard Taylor, described the fruit was prized by the natives. In 1773, the British explorer,James Cook, brewed the first nativebeer atTamatea / Dusky Sound, by extracting the young tips of the tree's branches. Rimu was once the most harvested timber, popular for flooring, furniture making, wagon building, and other uses, before it was protected by law. The tree's timber has very durable and resilient texture. Rimu'sconservation status was assessed by theIUCN Red List in 2013 as "Least Concern", and its population trend was assessed as "Stable".
Dacrydium cupressinum (rimu) is a species ofdioecious (either male or female) evergreenconifer in the familyPodocarpaceae,[3] and usually reaches 35 metres (115 feet) in height, but may reach up to 60 m (200 ft) tall, and can have a stouttrunk up to 1.5–2 m (4 ft 11 in – 6 ft 7 in) in diameter.[3][4][5] The trunk is usually cylindrical and smooth.[6]D. cupressinum grows in anerect (occasionallyforked), and usually amonopodial manner, meaning it grows from the mainstem.[4] When reaching its maxium height, it is typically unbranched for 20 m (70 ft) of its height.[7] The tree exhibits a pyramid-like shape in the early growth stages, and thecrown of mature trees evolves into a domed shape, with the mainbranches spreading outwards or ascending.[4]
Itsbark is grey to dark-brown in colour, shedding in large, elongated, thick flakes. When the outer layers of bark flake off, a distinctive wavy pattern of parallel raised ridges is visible on the new bark beneath. These lines of ridges have been described as resembling thecontour lines on a topographic map. Areas of bark between the ridges have small pointed projections with porous tissue that allow air to penetrate the bark, providing oxygen to the cells of the tree beneath the bark.[8] The wood is typically a dark-red colour, gradually becoming a yellow-brown colour after exposure to sunlight.[3][5]D. cupressinum has an estimated lifespan of 600–800 years, but can reach 1000 years old, although some specimens examined at the foothills ofMount Ruapehu suggest it may live as long as 1200 years.[9][10]
D. cupressinum is characterised by its drooping and hanging foliage.[4][11] Juvenile branches are slender, with hangingbranchlets. In adult specimens, there are fewer branches, which are spreading, and also have slender and hanging branchlets. The tree'sleaves vary in colour from dark-green to bronze-green, red-green, or in some cases orange. They are typically a yellowish-green colour and about 4 mm long, and arranged in an overlapping pattern (imbricated). Juvenile leaves measure 4–7–(10) millimetres in length and 0.5–1 mm in width. They are acute, long and narrow, slightly curved, and vaguely sickle-shaped (subfalcate) in character.[5][12] Subadult leaves are ascending and are 4–6 mm long. Adult leaves are similar, but they are flattened down (appressed), rigid, and aretriangular in shape.[3][5]
Like all conifers,D. cupressinum does not have flowers, but instead has cones (strobili); with male and female examples first seen on subadult specimens. In male specimens, cones are solitary or paired, terminal, measuring 5–10 mm, and are oblong in shape, producing yellowpollen. The tree'sovules (female reproductive structures) are solitary and at the tip of up-curved branchlets. Itsreceptacles (fleshy fruit-holding structures) form a cup that is red or deep-orange in colour and measures about 1–2 mm in length.[5][12] The pollen cones are found at the tips of branches and are oval to oblong in shape, measuring 7–10 mm long and 4 mm wide. Each pollen-bearing leaf (microsporophyll) has a pointed tip, is green in colour, and is 2–2.5 mm long. At its base, it holds two yellow pollen sacs.[4]
Fruiting takes over a year to mature and often coincides with the presence of young female cones. The fruits are most commonly seen between February and May.[5]D. cupressinum is a morphologically distinctive species, although it is sometimes misidentified with theseedlings ofManoao colensoi, which instead have glossier, coarser leaves.[5] The tree's seed cones grow at the ends of short, curved branchlets or on the sides, measuring about 6–10 mm long. Thebracts (specialised leaves) attached are short and barely visible when the cones mature into a swollen, orange to red colour. The tree's seeds are ovoid in shape, dark brown to black in colour, slightly flattened, are tiny at about 4–5 mm long, and they ripen to a black colour.[4][5]D. cupressinum has a geneticdiploid chromosome count of 20.[3]
In terms of chemical composition, the foliage ofD. cupressinum contains varioussesquiterpenes, with their levels showing significant variation between specimens, which is similar to the differences observed inditerpene levels. There are twelve known sesquiterpenes in the tree that have been identified by a 1985 study, but none of which show any structural similarity tolauren-1-ene.[13] The distinctive diterpene lauren-1-ene was first discovered in the foliage of the tree, however, the concentration of thiscompound, along with other diterpenes, also shows significant variation betweenD. cupressinum specimens.[14]
D. cupressinum contains high levels of the unique sesquiterpeneterpene compounds of9-epi-β-caryophyllene.[15] The tree also has a distinctiveflavonoid glycoside profile; the tree possesses flavonol-3-O-rhamnoglucosides and also, to a lesser extent, 3-0-methyl-myricetinglycoside compounds.[16]
_-_drooping_and_hanging_foliage.jpg)
.jpg)
| Phylogeny ofDacrydium | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Cladogram of thephylogenetical reconstruction of the genusDacrydium, from research published in 2021. |
Dacrydium cupressinum is the only member of the genusDacrydium native to New Zealand.[17] A 1998 study on thephylogeny of the Podocarpaceae family examined theevolution ofD. cupressinum and various other species. The research identified it as sister to aclade (group) consisting of various other Podocarpaceae species, including members of the genusDacrycarpus andPodocarpus. This discovery revealed thatD. cupressinum shares a common biological ancestor with these genera, while maintaining its evolutionary uniqueness.[18]
A 2020 study suggested that theDacrydium genus originated inNew Caledonia, based on a historical biogeographic reconstruction. Despite this, macrofossil evidence strongly supports a more broaderAustralasian origin, and another study also suggests thatDacrydium originated in Australasia during theLate Cretaceous epoch and dispersed intoSoutheast Asia in theEarly Oligocene.[19][20] Stull et al. 2021 investigated the role of plant evolution, analysing how ecological changes have shaped biodiversity and trait development over long timescales. In the study, they revealed thatpolyploidy is a primary driver of microevolution in plants, but its broader impact on macroevolutionary diversification and phenotypic innovation remains uncertain. In the study, researchers produced an ancestral reconstruction ofgymnosperms usingRNA sequencing.[21]D. cupressinum is thetype species of thegenusDacrydium.[5][22]
The nameD. cupressinum was first publishedinvalidly in 1786 by the European naturalistGeorg Forster, using a description byDaniel Solander, in a publication entitled,De Plantis Esculentis Insularum Oceani Australis Commentatio Botanica.[23][24] The British botanistAylmer Lambert provided the first validdescription of the species in his 1806 work,A Description of the Genus Pinus.[25] The name,Thalamia cupressina, comes from a later 1826 description ofD. cupressinum whereKurt Sprengel attempted to place the taxon,D. cupressinum into the genus,Thalamia. His placement has not been accepted by other plant taxonomists, and hence the name given by Sprengel becomes a homotypic synonym.[2][26] In 1855, French botanistÉlie-Abel Carrière described the speciesDacrydium cupressiforme, in his workTraité Général des Conifères.[27] What he thought to be a new species is now recognised as beingDacrydium cupressinum and hence is a heterotypic synonym of the species described earlier in 1806.[2]
Theetymology (word origin) ofD. cupressinum's genus,Dacrydium, comes from theGreekdakryon (δάκρυδον), which translates to 'tear-drop' or simply 'tear';[28][22] one possibility, suggested by Dutch botanistAljos Farjon, stated that the genus name could be in reference to theresinous drops exuded by the tree.[5][22] However, English-born botanistThomas Kirk, in his 1889 revision titledThe Forest Flora of New Zealand, instead hypothesised thatDacrydium is in reference to the weeping habit of the trees.[29] Thespecific epithet (second part of the scientific name),cupressinum, translates simply to 'cypress'; which refers to the tree's similarity withCupressus species.[17]D. cupressinum iscommonly known as rimu.[5][30] The word rimu (or limu) is typically used inPolynesian languages to describe seaweeds and mosses; it is likely that the name was applied to the tree due to the similarity of the tree's leaves to seaweed.[17]
D. cupressinum's seeds aredispersed by gravity and by fruit-eating animals (frugivores).[31] These seeds are well-adapted to be dispersed by birds; primary dispersers of the seeds includebellbirds,kererū, and thetūī.[32][33]Brown creepers,fantails,grey warblers,riflemen,silvereyes, andtomtits have been observed in association with the tree.[34] Other birds, such aswhite-eyes andhouse sparrows, feed on the tree's receptacles (fleshy fruit-like structures).[35] The tree is known to be browsed bydeer andpossums, which browse the seedlings and consume the foliage and branchlets, respectively.[7][36] Excrements of thewētā are frequently found inseed traps, which could indicate that wētā consume the seeds of the tree.[35] The seeds have been recorded being destroyed by chaffinches, mice, rats, and wētā.[37]
D. cupressinum's fruits are an important food and vitamin resource for the native flightless parrot, thekākāpō, which feeds on the fruits.[17][38] The fruits are high in calcium and vitamins, and the kākāpō may have adapted to survive prolonged periods of limited access to these resources.[39] The kākāpō will onlymate during years of heavy fruiting.[40][41]
Several species of insects have been recorded as feeding on the stems and leaves, including:stick insects,weevils,Pyrgotis species, and looper caterpillars, fromPseudocoremia fenerata. Other wood-boring insects onD. cupressinum include:Ambeodontus tristis,Calliprason pallidus,Prionoplus reticularis,Rhynchodes ursus, andPlatypus species.[42] The tree also serves as a host for twobeetle species,Euderia squamosa andSommatidia antarctica, both of which lay their eggs and feed on the tree.[35][43] Despite these two beetles sharing similar life cycles, certain distinguishing features allow for the differentiation between their infestations and association with the tree.[44] Thelarvae ofOtiorhynchus sulcatus, an introduced species of weevil, can cause damage to seedling'sroots in nursery beds.[35]D. cupressinum is very sensitive to fire and is one of the most flammable New Zealand tree species. It is likely the tree has not evolved to be resistant against fire or develop particular traits against flammability, as fire is uncommon in the communities where the tree grows.[42][45]D. cupressinum is a very wind-resistant tree, particularly when growing on deep soils. However, if damaged, the trees will not regrow by producingcoppice shoots, which is a tree regrowth method by producing newshoots.[42]
D. cupressinum serves as ahost for numerous vascularepiphytes, which are plants that grow on other plants.Metrosideros robusta is perhaps one of the most prominent epiphyte species in the North Island and the northern South Island, in which it takes root in the tree, extending its roots downward to reach the ground. Over time,M. robusta can eventually replace its host as the original tree due to old age or suppression.[42] Other common species that grow as epiphytes on the tree includesAstelia solandri andGriselinia lucida.[42] The New Zealand naturalistWalter Oliver conducted a study in 1930 of epiphyte andhemi-epiphyte relationships withD. cupressinum in Gollans Valley, nearWellington. Oliver documented eleven and twelve species in a sunny habitat and a shady habitat, respectively, as epiphytes on the tree. Oliver also mentioned thatNothopanax arboreum, a hemi-epiphyte species, was common.[46]
The New Zealand mycologist,G. H. Cunningham, recorded thirty-eight species ofThelephoraceae and twenty-seven species ofPolyporaceae assaprophytes onD. cupressinum.[42] The most commonfungi associated with the tree, according to a 2012 study in theNew Zealand Journal of Botany, areArmillaria novae-zelandiae andGanoderma applanatum. The fungi species that were recorded to a lesser extent included:Hypochnicium polonense,Rigidoporus concrescens, andIrpex species.[47]Armillaria mellea is the only species of fungus known to beparasitic to the tree.[35] A 2009 study of the fungalendophytes on various Podocarpaceae species revealed thatD. cupressinum had the highest diversity of endophytes among the studied species; several fungi genera mentioned as hosts onD. cupressinum were:Colletotrichum,Cylindrobasidium,Ophiognomonia,Pezicula,Phomopsis,Phyllosticta, andXylaria.[48] Themycorrhizal fungi nodules ofDacrydium species are small, at about 0.5–0.7 mm (0.020–0.028 in) in diameter.[42]
D. cupressinum ispollinated by the wind.[32][49]D. cupressinum's seeds typically remain dormant for at least 30 days, but sometimes much longer prior togermination.[37] Beveridge (1964) estimates that a mature specimen would possess about 18 kg (40 lb) of ripe seeds and receptacles or 1.8 kg (4.0 lb) of clean sound seeds, ultimately producing about 200,000 seeds.[9][50] The seedsripen between March and May, about 15–18 months following pollination and are later dispersed for over 1–2 months, although infertile seeds may continue to be released for a significantly longer duration.[32]D. cupressinum's seedlings will not establish themselves where there is moderate to severeroot competition and a moderately densecanopy because oflow light intensities. The tree prefers sites with partial shade.[32][51]
D. cupressinum is known for exhibitingmast seeding, which is the synchronised periodicity of seed production.[49] In the Pureora Forest and the Wanganui Forest, in the North Island and the South Island, respectively, seedfall data show clear yearly fluctuations in seed production in studied specimens.[33] A 1988 study proposes that a combination of low seed production and cool temperatures two years before, followed by warm temperatures during seedfall are necessary, but not solely responsible for triggering a mast year in the tree. The relationship between seed production in one year and conditions from two years earlier also plays an important role.[33][52] Canham et al. 2014 analysedD. cupressinum specimens growing in less fertile marine terrace sites had a higher seed production rate in comparison to specimens that grew on more fertile alluvial soils. Researchers suggested that the tree has adapted to seed production in less fertile soils rather than being displaced by other species.[53]
Thegrowth rates ofD. cupressinum can vary significantly, especially in the early growth stages. Height growth often occurs at the expense of diameter growth, with saplings limited to 10 cm (3.9 in) in diameter and reaching up to 12 m (39 ft) tall. In open conditions, annual increments can be 15–30 cm (5.9–11.8 in) in height and 1–3 cm (0.39–1.18 in) in diameter, but growth rate slows in shaded forest environments, with seedlings growing 1–2 cm (0.39–0.79 in) per year.[9]
_near_Haupiri.jpg)
D. cupressinum isendemic to New Zealand, and is the country's most common native conifer.[5][54] Itsrange covers theNorth Island,South Island, andStewart Island. In the South Island, it is uncommon or absent in parts of the eastern side of the island. On theBanks Peninsula, it is almost entirelyextinct, with its absence being attributed to deforestations instead of environmental changes, such as moisture deficits in summer.[5][55]D. cupressinum was previously common around the Banks Peninsula town ofLittle River.[56] In the South Island,D. cupressinum's range predominantly covers the west side of the island, and it is largely not present in:Canterbury,Marlborough,Otago, and more generally, the inland South Island.[56][57]
D. cupressinum was likely naturally not present in only a few specific areas of the North Island prior to colonisation, which included: the eastern parts ofTongariro National Park,Kaingaroa Forest, and the southern parts ofHawke's Bay.[56] On the eastern side of the South Island, the tree's presence is scattered, particularly in the areas in betweenBlenheim andWaikouaiti. The species does occur in small populations in theAshley Forest, theHunters Hills, theKaikōura Ranges, and a few other localities.[56]
D. cupressinum typically inhabits lowland tomontane forests, and is occasionally found nearsubalpine scrubland.[5] The tree is a dominant or codominant tree in mixed conifer or conifer-angiosperm forests, reaching elevations of up to 700–950 m (2,300–3,120 ft) above sea level. Its lower elevation limits are 10 m (30 ft) above sea level. The tree is commonly associated with other conifers in its natural habitat, such as: kauri (Agathis australis) and tōtara (Podocarpus totara), as well asangiosperms, which could include: taraire (Beilschmiedia tarairi) and variousMetrosideros species.[1][57]D. cupressinum has a highly varied climatic range and can grow in mostsoil types, but it will grow faster in more fertile soils.[56] In theWest Coast Region, the tree grows in areas of heavy rainfall onboulder clay, and soils that are rich inhumus.[58] The seedlings of the tree also appear to have a preference for soils that are rich in humus and minerals.[59] Unlike other members of theDacrydium genus,D. cupressinum is the only member of the genus that is naturally found in atemperate climate.[60]
D. cupressinum has played a significant role in both the Māori and European cultures of New Zealand. In 1773, the British explorer,James Cook, brewed the first nativebeer atTamatea / Dusky Sound, extracting the young tips of the branches of the tree to create what was known as "spruce beer".[5][29] Cook's beer was an efficient source to preventscurvy, a deficiency disease.[11][17] The British missionary,Richard Taylor, in a book on the cultural and natural history of New Zealand plants published in 1848, describedD. cupressinum's fruit as being prized by the natives and observed that infusions of its wood were used for making beer. He also noted that resin from the tree was "sweet and bitter".[61]
The former vernacular name used by European settlers, the 'red pine', which refers to the deep red colour of the sap and wood of the tree, has since fallen out of common use.[17]
D. cupressinum served as a significant source oftimber in New Zealand, because the tree was present throughout many lowland parts of the country and the trees could grow to large sizes.[1][42]D. cupressinum was once the most harvested timber in New Zealand, consisting of 58 percent of the country's total timber production between 1918 and 1930. The timber has been used for furniture making, and the interior panelling of trams and railway-cars.[54][62] The timber has also been used for other miscellaneous purposes, such as ceiling bases, coffins, and picture-frames.[62]
The timber has a uniform texture and it is very durable and resilient.[1][63] In a 1931 revision of the tree's properties of the wood, it was called the "most important softwood in New Zealand".[63] The timber was frequently chosen for decorative purposes; the timber merges the qualities of a texturedhardwood with the moderate weight of a commonsoftwood.D. cupressinum's primary roles as a timber include it being used for fencing, flooring, furniture making, wagon-building, and weatherboards. Theheartwood is durable above ground, but the sapwood is prone to decaying in wet environments and vulnerable to infestations by beetles.[64][65]
... [this fruit] is much prized by the natives, the smallness of the size being made up by its abundance; this tree produces a resin which is both sweet and bitter; the wood, also, possesses the same qualities; an infusion might be used for beer.
InMāori mythology, when the Polynesian explorerKupe first discovered New Zealand, Nukutawhiti, an important ancestor, performed a ceremony when reaching land using theshoots from the tree in the presence of traditional Polynesian immortals, before people from his canoe could go ashore.[66]D. cupressinum is of great importance toMāori, the indigenous people of New Zealand.[61][67] The fruit is abundant during the fruiting season, and served as a significant food source to Māori.[68][69] TheNgāpuhi people (tribe) used the timber for canoe-making (orwaka).D. cupressinum was also usedmedicinally by Māori: itsgum (or sap) was used as astyptic to stop bleeding fromwounds; its bark was utilised fordecoction to treat wounds, and the inner parts of the bark were crushed into a pulp to treatburns; and its leaves were used to treat sores.[69] Māori have long seen the value of the timber for creating weapons.[67] The British missionary,William Colenso, recorded that "long war spears" were made from the timber.[70] The timber was also crafted into hunting spears.[69]
There are some other more names that Māori have for specific parts of the tree; for example, the tree's heartwood is known as:kāpara,māpara, orngāpara. The fruit is known ashuarangi, and the seed inside the fruit was known asmatawhanaunga.[69] Another name some Māori used for the tree waspuaka, which the ethnographerElsdon Best documented as being used by theTe Arawa people (aniwi from the North Island).[71]
D. cupressinum'sconservation status was assessed by theIUCN Red List in 2013 as "Least Concern", and its population trend was assessed as "Stable".[1] Its assessment in theNew Zealand Threat Classification System was evaluated in 2023 as "Not Threatened".[5] Although previously harvested for timber,D. cupressinum is now protected fromlogging under theForests Act 1949, which was amended in 1993, and its natural regeneration is vigorous in locations with mature trees and is further supported byrevegetation efforts.[1][72]D. cupressinum timber is still produced, although in smaller amounts.[72]
The current threats that the tree possesses areintroduced species, such asdeer andpossums.[1] A significant amount of lowland forests in New Zealand were historically cleared for agriculture, forestry, and urban growth over 150 years, ending around 1970. This has led to at least a 70 percent decline in the area occupied by the tree and other plant species, making the species eligible as "Endangered" under IUCN guidelines. However, some conservationists argue that threat assessments should focus on present and future conditions, making the classification controversial.[30] Despite this, the 2013 classification on the ICUN Red List remains "Least Concern".[1]
Books
Journals
Websites
Media related toDacrydium cupressinum at Wikimedia Commons| National | |
|---|---|
| Other | |
