''Ileostylus micranthus'', commonly known as green mistletoe pikirangi; pirinoa; pirirangi; pirita; small-flowered mistletoe, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of mistletoe in the family

Loranthaceae Loranthaceae, commonly known as the showy mistletoes, is a family of flowering plants. It consists of about 75 genera and 1,000 species of woody plants, many of them hemiparasites. The three terrestrial species are '' Nuytsia floribunda'' (the ...

Description

''Ileostylus micranthus'' is a mistletoe native to

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 ...

and the

Norfolk Island Norfolk Island ( , ; ) is an States and territories of Australia, external territory of Australia located in the Pacific Ocean between New Zealand and New Caledonia, directly east of Australia's Evans Head, New South Wales, Evans Head and a ...

s. In New Zealand it is also known by its

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 ...

name Pirita. Mistletoes are

stem Stem or STEM most commonly refers to: * Plant stem, a structural axis of a vascular plant * Stem group * Science, technology, engineering, and mathematics Stem or STEM can also refer to: Language and writing * Word stem, part of a word respon ...

hemiparasites that live on the limbs of a host tree or shrub and consume water,

nutrient A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...

s transported by water, and organic

solutes In chemistry, a solution is defined by IUPAC as "A liquid or solid phase containing more than one substance, when for convenience one (or more) substance, which is called the solvent, is treated differently from the other substances, which are ...

. The

and

Viscaceae Viscaceae is a taxonomic family name of flowering plants. In this circumscription, the family includes the several genera of mistletoes. This family name is currently being studied and under review as in past decades, several systems of plant tax ...

are the two main groups of mistletoe. Loranthaceae contains 50 to 80

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

, which are primarily Southern Hemisphere-based. There are six

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

Loranthaceae species in New Zealand. Since European settlement, all have decreased in abundance. Loss of territory and the introduction of

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

s, particularly the Australian

brushtail possum The brushtail possums are the members of the genus ''Trichosurus'' in the Phalangeridae, a family of marsupials. They are native to Australia (including Tasmania) and some small nearby islands. Unique among marsupials, they have shifted the hyp ...

, have caused the decline. ''Ileostylus micranthus'' grows in clusters on their

host plant In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include a ...

with a diameter of at least 2 m. It has opposite pairs of thick, leathery

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

with a leaf length between 2 cm and 8 cm and a width of 1 to 3 cm. The leaves have smooth edges, no visible veining, and a rounded shape. Young

branchlet A branch, also called a ramus in botany, is a stem that grows off from another stem, or when structures like veins in leaves are divided into smaller veins. History and etymology In Old English, there are numerous words for branch, includ ...

s are curved and green. The flowers are tiny (3–5 mm in diameter), greenish-yellow, and lightly scented. When the yellow fruit has matured, it is rounded with about a 6-mm diameter. The ripe fruit has green interior

flesh Flesh is any aggregation of soft tissues of an organism. Various multicellular organisms have soft tissues that may be called "flesh". In mammals, including humans, ''flesh'' encompasses muscles, fats and other loose connective tissues, ...

and one sticky

seed In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...

Distribution

''Ileostylus micranthus'' occurs on

with a status of

vulnerability Vulnerability refers to "the quality or state of being exposed to the possibility of being attacked or harmed, either physically or emotionally." The understanding of social and environmental vulnerability, as a methodological approach, involves ...

under The Environment Protection and Biodiversity Conservation Act 1999. ''Ileostylus micranthus'' arrived on Norfolk Island from New Zealand in the 1930s, apparently unaided. There are few records of ''Ileostylus'' on Norfolk Island but a larger abundance in New Zealand, where it can be found 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 ...

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 ...

and

Stewart Island Stewart Island (, ' 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 with a la ...

. ''Ileostylus micranthus'' can be found in New Zealand in locations that include the Northland Podocarpus totara forests, the

Rotorua Rotorua () is a city in the Bay of Plenty region of New Zealand's North Island. It is sited on the southern shores of Lake Rotorua, from which it takes its name. It is the seat of the Rotorua Lakes District, a territorial authorities of New Zea ...

Taupō Taupō (), sometimes written Taupo, is a town located in the central North Island of New Zealand. It is situated on the edge of Lake Taupō, which is the largest freshwater lake in New Zealand. Taupō was constituted as a borough in 1953. It h ...

area of the

Taupō Volcanic Zone The Taupō Volcanic Zone (TVZ) is a volcano, volcanic area in the North Island of New Zealand. It has been active for at least the past two million years and is still highly active. Mount Ruapehu marks its south-western end and the zone runs n ...

's regenerating scrub and

forest A forest is an ecosystem characterized by a dense ecological community, community of trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, ...

, as well as the grey-scrub communities of

Marlborough Marlborough or the Marlborough may refer to: Places Australia * Marlborough, Queensland * Principality of Marlborough, a short-lived micronation in 1993 * Marlborough Highway, Tasmania; Malborough was an historic name for the place at the sou ...

Kaikōura Kaikōura (; ) is a town on the east coast of the South Island of New Zealand, located on New Zealand State Highway 1, State Highway 1, north of Christchurch. The town has an estimated permanent resident population of as of . Kaikōura is th ...

Banks Peninsula Banks Peninsula () is a rocky peninsula on the east coast of the South Island of New Zealand that was formed by two now-extinct volcanoes. It has an area of approximately . It includes two large deep-water harbours — Lyttelton Harbour a ...

Central Otago Central Otago is an area located in the inland part of the Otago region in the South Island of New Zealand. The motto for the area is "A World of Difference". The area is dominated by mountain ranges and the upper reaches of the Clutha River ...

(the Lake District), and

Dunedin Dunedin ( ; ) is the second-most populous city in the South Island of New Zealand (after Christchurch), and the principal city of the Otago region. Its name comes from ("fort of Edin"), the Scottish Gaelic name for Edinburgh, the capital of S ...

. ''Ileostylus'' is also frequently connected to

Cook Strait Cook Strait () is a strait that separates the North Island, North and South Islands of New Zealand. The strait connects the Tasman Sea on the northwest with the South Pacific Ocean on the southeast. It is wide at its narrowest point,McLintock, ...

's coastal forests, saline marches, and portions of

Nelson Nelson may refer to: Arts and entertainment * ''Nelson'' (1918 film), a historical film directed by Maurice Elvey * ''Nelson'' (1926 film), a historical film directed by Walter Summers * ''Nelson'' (opera), an opera by Lennox Berkeley to a lib ...

and Westland.

Habitat

''Ileostylus micranthus'' occurs mostly in the lowland districts in the

and

. The distribution of this

indicates that it prefers lowland environments and that there is no clear national

correlation In statistics, correlation or dependence is any statistical relationship, whether causal or not, between two random variables or bivariate data. Although in the broadest sense, "correlation" may indicate any type of association, in statistics ...

between it and any host. ''Ileostylus micranthus'' compared to other parasitizing mistletoes within

is newly introduced. The variability of spatial and temporal host availability since its arrival has appeared to have the most favored host generalization. There are two modes of important

evolutionary Evolution is the change in the heritable characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certa ...

variety for

parasites Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The en ...

which are co-speciation and host-switching. ''Ileostylus micranthus'' appears to have no host specialization due to having records of parasitizing

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

over 209

including 92

exotic species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

and three

that are restricted to

Ecology

''Ileostylus micranthus'' has unique physiological characteristics and morphological structures that assist them to develop connections with its host plants.

Water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

organic acids An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO2OH, are r ...

ions An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

sugars Sugar is the generic name for Sweetness, sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides ...

minerals In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): M ...

and

amino acids Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the Proteinogenic amino acid, 22 α-amino acids incorporated into p ...

can be easily

transported ''Transported'' is an Australian convict melodrama film directed by W. J. Lincoln. It is considered a lost film. Plot In England, Jessie Grey is about to marry Leonard Lincoln but the evil Harold Hawk tries to force her to marry him and she ...

through the connections made by the

vascular Vascular can refer to: * blood vessels, the vascular system in animals * vascular tissue Vascular tissue is a complex transporting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue ...

connection points. The

nutrients A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...

required for attachment and the growth of the first

photosynthetic Photosynthesis ( ) is a Biological system, system of biological processes by which Photoautotrophism, photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical ener ...

structures are supplied by maternal reserves when an ''Ileostylus micranthus''

is dispersed by

birds Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

to the host branch. ''Ileostylus micranthus'' has viscous seeds meaning that it has a thick residue surrounding the exterior of the seed. This is an adaptation to adhere to the host species and the

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

then needs to establish a connection with the host in order to continue functioning. Once the

has become established, the

hypocotyl The hypocotyl (short for "hypocotyledonous stem", meaning "below seed leaf") is the stem of a germinating seedling, found below the cotyledons (seed leaves) and above the radicle (root). Eudicots As the plant embryo grows at germination, it send ...

straightens and pulls the two

cotyledon A cotyledon ( ; ; "a cavity, small cup, any cup-shaped hollow", gen. (), ) is a "seed leaf" – a significant part of the embryo within the seed of a plant – and is formally defined as "the embryonic leaf in seed-bearing plants, one or mor ...

s out of the endosperm. The first pair of true leaves usually develop around four weeks after the initial pair of small green cotyledons, which function as leaves. Fully developed ''Ileostylus micranthus'' plants have a high use of water and nutrients (N and P), wide stomata and low stomatal density. Low stomatal density impacts and influences the plant's characteristics for plant growth which can be calculated by the stomata number per unit leaf area. ''Ileostylus micranthus'' accumulates the host plant species’ nutrients ( C, K, N, P, Ca, and Mg) into their own tissues by making them soluble. This process takes the host plant species’ reserves of non-structural

carbohydrate A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' ...

s, negatively impacting the efficiency of the host plant processes.

Silvereye The silvereye or wax-eye (''Zosterops lateralis''), also known by its Māori name tauhou, is a very small omnivorous passerine bird of the south-west Pacific. In Australia and New Zealand its common name is sometimes white-eye, but this name is ...

s, bellbirds, and tui are the three most significant avian dispersers of the ''Ileostylus micranthu'' seeds. The fruits are swallowed whole, and the seeds later became defecated in a germinal state. These birds tend to frequent plants for only 1–2 minutes, eating a few mistletoe fruits each time. Seeds fail to

germinate Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an flowering plant, angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the sp ...

unless the fruit exterior, or

exocarp Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Fruitlike structures may develop directly from the seed itself rather th ...

, is removed, either manually or by passing through the gut of a bird. The only method of exocarp removal that is successful in the field is bird dispersal, even though hand removal of the exocarp can result in a germination rate that was equal to or higher than that of bird removal. If the fruit of the ''Ileostylus micranthus'' has not been consumed by avian dispersers, the fruit will overripen and fall off the fruit stalk and rot, negatively impacting the

germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, ...

and success of the seed. ''Ileostylus micranthus'' have unspecialized flowers which means that native and or introduced insect

can pollinate. Flowering occurs between September and December and fruiting occurs between the months of April and June.

Predators, parasites, and diseases

Native

are less prevalent than they were a

century A century is a period of 100 years or 10 decades. Centuries are numbered ordinally in English and many other languages. The word ''century'' comes from the Latin ''centum'', meaning ''one hundred''. ''Century'' is sometimes abbreviated as c. ...

ago in many parts of

. The

traditional A tradition is a system of beliefs or behaviors (folk custom) passed down within a group of people or society with symbolic meaning or special significance with origins in the past. A component of cultural expressions and folklore, common examp ...

explanation for this decline is that

habitat destruction Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

and, more recently, possum

browsing Browsing is a kind of orienting strategy. It is supposed to identify something of relevance for the browsing organism. In context of humans, it is a metaphor taken from the animal kingdom. It is used, for example, about people browsing open sh ...

is to blame. Native avian

(and the self-introduced

silvereye The silvereye or wax-eye (''Zosterops lateralis''), also known by its Māori name tauhou, is a very small omnivorous passerine bird of the south-west Pacific. In Australia and New Zealand its common name is sometimes white-eye, but this name is ...

) almost entirely carry out dispersal. Introduced

frugivorous A frugivore ( ) is an animal that thrives mostly on raw fruits or succulent fruit-like produce of plants such as roots, shoots, nuts and seeds. Approximately 20% of mammalian herbivores eat fruit. Frugivores are highly dependent on the abundance ...

, like blackbirds and

thrushes The thrushes are a passerine bird family, Turdidae, with a worldwide distribution. The family was once much larger before biologists reclassified the former subfamily Saxicolinae, which includes the chats and European robins, as Old World flycat ...

, eat scant amounts of

mistletoe Mistletoe is the common name for obligate parasite, obligate parasitic plant, hemiparasitic plants in the Order (biology), order Santalales. They are attached to their host tree or shrub by a structure called the haustorium, through which they ...

fruit and cannot make up for the decline in native

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

populations Population is a set of humans or other organisms in a given region or area. Governments conduct a census to quantify the resident population size within a given jurisdiction. The term is also applied to non-human animals, microorganisms, and pl ...

brought on by the arrival of

mammalian A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

predators Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

Fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...

production is partially limited to the dispersal of the amount of

availability. This could be related to a number of factors such as the competitive interactions being increased by the introduction of new

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

which are using

resources ''Resource'' refers to all the materials available in our environment which are Technology, technologically accessible, Economics, economically feasible and Culture, culturally Sustainability, sustainable and help us to satisfy our needs and want ...

such as honeydew for the intention of

food supply Food security is the state of having reliable access to a sufficient quantity of affordable, healthy food. The availability of food for people of any class, gender, ethnicity, or religion is another element of food protection. Similarly, househo ...

. As well as the overall densities of avian dispersers to fulfil the mutual relationship that the ''Ileostylus micranthus'' creates with birds ( Tui, bellbird,

and introduced

). Predators can impact the ''Ileostylus micranthus'' indirectly and directly. Indirectly, mammalian introduced species can negatively impact the population of seed dispersers (native and introduced

). ''Ileostylus micranthus'' relies heavily on the seed dispersers to reach their host species and to be able to attach to the host species (removal of the

). Tui and other native bird species fluctuate in population densities, which the change in population can be a strong influence on ''Ileostylus micranthus'' success. Due to impacting the rate of reproduction and survival for ''Ileostylus micranthus''. Avian seedvdispersers are facing an increase in

habitat loss Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

and non-native mammalian predators including the Norway rat (''

Rattus norvegicus ''Rattus'' is a genus of muroid rodents, all typically called rats. However, the term rat can also be applied to rodent species outside of this genus. Species and description The best-known ''Rattus'' species are the black rat (''R. rattus' ...

),'' Polynesian rat (''

Rattus exulans The Polynesian rat, Pacific rat or little rat (''Rattus exulans''), or , is the third most widespread species of rat in the world behind the brown rat and black rat. Contrary to its vernacular name, the Polynesian rat originated in Southeast Asia ...

)'' and the Ship rat (''

Rattus ''Rattus'' is a genus of muroid rodents, all typically called rats. However, the term rat can also be applied to rodent species outside of this genus. Species and description The best-known ''Rattus'' species are the black rat (''R. rattus'') ...

).'' Other

that are predators include the Brushtail possums (''

Trichosurus vulpecula The common brushtail possum (''Trichosurus vulpecula'', from the Greek for "furry tailed" and the Latin for "little fox", previously in the genus ''Phalangista'') is a nocturnal, semiarboreal marsupial of the family Phalangeridae, native to Aus ...

),'' Cats ''(''

Felis catus The cat (''Felis catus''), also referred to as the domestic cat or house cat, is a small domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the d ...

), Mustlelids and Mice ''(

Mus musculus The house mouse (''Mus musculus'') is a small mammal of the rodent family Muridae, characteristically having a pointed snout, large rounded ears, and a long and almost hairless tail. It is one of the most abundant species of the genus ''Mus (genu ...

)'' which all

prey Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not ki ...

on the dependable ''Ileostylus micranthus'' seed dispersers. The direct effect of these mammalian

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

is the predation of the ''Ileostylus micranthus'' flowers and seeds, These predators impact the

reproduction Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. There are two forms of reproduction: Asexual reproduction, asexual and Sexual ...

and

survival Survival or survivorship, the act of surviving, is the propensity of something to continue existing, particularly when this is done despite conditions that might kill or destroy it. The concept can be applied to humans and other living things ...

rate due to the disturbance of the

process (avian dispersers are unable to digest the seeds to remove the

for

). To be able to conserve and maintain the ''Ileostylus micranthus'' population, measures need to be implemented to ensure that the avian seed dispersers maintain or increase population densities to increase the

and

reproductive The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are al ...

rate of ''Ileostylus micranthus.''

References

{{Taxonbar, from=Q18075063 Loranthaceae Flora of New Zealand