Cyathus stercoreus Fruchtkörper.JPG
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''Cyathus'' is a genus of fungi in the Nidulariaceae, a family collectively known as the bird's nest fungi. They are given this name since they resemble tiny bird's nests filled with "eggs", structures large enough to have been mistaken in the past for seeds. However, these are now known to be reproductive structures containing
spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...
s. The "eggs", or ''peridioles'', are firmly attached to the inner surface of this
fruit body In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the Ovary (plants), ovary after flowering plant, flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their ...
by an elastic cord of mycelia known as a funiculus. The 45 species are widely distributed throughout the world and some are found in most countries, although a few exist in only one or two locales. ''
Cyathus stercoreus ''Cyathus stercoreus'', commonly known as the dung-loving bird's nest or the dung bird's nest, is a species of fungus in the genus '' Cyathus'', family Nidulariaceae. Like other species in the Nidulariaceae, the fruiting bodies of ''C. sterc ...
'' is considered endangered in a number of European countries. Species of ''Cyathus'' are also known as splash cups, which refers to the fact that falling raindrops can knock the peridioles out of the open-cup fruit body. The internal and external surfaces of this cup may be ridged longitudinally (referred to as
plicate Plicata, ''plicate'', ''plicated'', ''pleated'' or ''folded'' in Latin, may refer to: * Lingua plicata, a benign condition characterized by deep grooves in the dorsum of the tongue * Pars plicata The pars plicata (also known as corona ciliaris ) ...
or striate); this is one example of a
taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
characteristic that has traditionally served to distinguish between species. Generally considered inedible, ''Cyathus'' species are saprobic, since they obtain nutrients from decomposing
organic matter Organic matter, organic material, or natural organic matter refers to the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have c ...
. They usually grow on decaying wood or woody debris, on cow and horse dung, or directly on
humus In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Lati ...
-rich soil. The life cycle of this genus allows it to reproduce both sexually, with meiosis, and asexually via spores. Several ''Cyathus'' species produce bioactive compounds, some with medicinal properties, and several
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...
-degrading enzymes from the genus may be useful in bioremediation and agriculture. Phylogenetic analysis is providing new insights into the evolutionary relationships between the various species in ''Cyathus'', and has cast doubt on the validity of the older
classification Classification is a process related to categorization, the process in which ideas and objects are recognized, differentiated and understood. Classification is the grouping of related facts into classes. It may also refer to: Business, organizat ...
systems that are based on traditional taxonomic characteristics


Taxonomy


History

Bird's nest fungi were first mentioned by Flemish botanist Carolus Clusius in ''Rariorum plantarum historia'' (1601). Over the next couple of centuries, these fungi were the subject of some controversy regarding whether the peridioles were seeds, and the mechanism by which they were dispersed in nature. For example, the French botanist Jean-Jacques Paulet, in his work ''Traité des champignons'' (1790–3), proposed the erroneous notion that peridioles were ejected from the fruit bodies by some sort of spring mechanism.Brodie (1975), p. 15. The genus was established in 1768 by the Swiss scientist
Albrecht von Haller Albrecht von Haller (also known as Albertus de Haller; 16 October 170812 December 1777) was a Swiss anatomist, physiologist, naturalist, encyclopedist, bibliographer and poet. A pupil of Herman Boerhaave, he is often referred to as "the fa ...
; the generic name ''Cyathus'' is Latin, but originally derived from the Ancient Greek word κύαθος, meaning "cup". The structure and biology of the genus ''Cyathus'' was better known by the mid-19th century, starting with the appearance in 1842 of a paper by Carl Johann Friedrich Schmitz, and two years later, a
monograph A monograph is a specialist work of writing (in contrast to reference works) or exhibition on a single subject or an aspect of a subject, often by a single author or artist, and usually on a scholarly subject. In library cataloging, ''monograph ...
by the brothers Louis René and Charles Tulasne. The work of the Tulasnes was thorough and accurate, and was highly regarded by later researchers. Subsequently, monographs were written in 1902 by Violet S. White (on American species),
Curtis Gates Lloyd Curtis Gates Lloyd (July 17, 1859 – November 11, 1926) was an American mycologist known for both his research on the gasteroid and polypore fungi, as well as his controversial views on naming conventions in taxonomy. He had a herbarium with ab ...
in 1906,
Gordon Herriot Cunningham Gordon Herriot Cunningham, CBE, FRS (27 August 1892 – 18 July 1962) was the first New Zealand-based mycologist and plant pathologist. In 1936 he was appointed the first director of the DSIR Plant Diseases Division. Cunningham established the ...
in 1924 (on New Zealand species), and Harold J. Brodie in 1975.


Infrageneric classification

The genus ''Cyathus'' was first subdivided into two infrageneric groups (i.e., grouping species below the rank of genus) by the Tulasne brothers; the "eucyathus" group had fruit bodies with inner surfaces folded into
pleat A pleat (plait in older English) is a type of fold formed by doubling fabric back upon itself and securing it in place. It is commonly used in clothing and upholstery to gather a wide piece of fabric to a narrower circumference. Pleats are cat ...
s (plications), while the "olla" group lacked plications. Later (1906),
Lloyd Lloyd, Lloyd's, or Lloyds may refer to: People * Lloyd (name), a variation of the Welsh word ' or ', which means "grey" or "brown" ** List of people with given name Lloyd ** List of people with surname Lloyd * Lloyd (singer) (born 1986), American ...
published a different concept of infrageneric grouping in ''Cyathus'', describing five groups, two in the eucyathus group and five in the olla group. In the 1970s, Brodie, in his monograph on bird's nest fungi, separated the genus ''Cyathus'' into seven related groups based on a number of
taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
characteristics, including the presence or absence of plications, the structure of the peridioles, the color of the fruit bodies, and the nature of the hairs on the outer peridium:
''Olla'' group: Species with a tomentum having fine flattened-down hairs, and no plications. * '' C. olla'', ''C. africanus'', ''C. badius'', ''C. canna'', ''C. colensoi'', ''C. confusus'', ''C. earlei'', ''C. hookeri'', ''C. microsporus'', ''C. minimus'', ''C. pygmaeus'' ''Pallidus'' group: Species with conspicuous, long, downward-pointing hairs, and a smooth (non-plicate) inner peridium. * ''C. pallidus'', ''C. julietae'' ''Triplex'' group: Species with mostly dark-colored peridia, and a silvery white inner surface. * ''C. triplex'', ''C. setosus'', ''C. sinensis'' ''Gracilis'' group: Species with tomentum hairs clumped into tufts or mounds. * ''C. gracilis'', ''C. intermedius'', ''C. crassimurus'', ''C. elmeri'' ''Stercoreus'' group: Species with non-plicate peridia, shaggy or wooly outer peridium walls, and dark to black peridioles. * ''C. stercoreus'', ''C. pictus'', ''C. fimicola'' ''Poeppigii'' group: Species with plicate internal peridial walls, hairy to shaggy outer walls, dark to black peridioles, and large, roughly spherical or ellipsoidal spores. * ''C. poeppigii'', ''C. crispus'', ''C. limbatus'', ''C. gayanus'', ''C. costatus'', ''C. cheliensis'', ''C. olivaceo-brunneus'' ''Striatus'' group: Species with plicate internal peridia, hairy to shaggy outer peridia, and mostly elliptical spores. * '' C. striatus'', ''C. annulatus'', ''C. berkeleyanus'', ''C. bulleri'', ''C. chevalieri'', ''C. ellipsoideus'', '' C. helenae'', ''C. montagnei'', ''C. nigro-albus'', ''C. novae-zeelandiae'', ''C. pullus'', ''C. rudis''


Phylogeny

The 2007 publication of phylogenetic analyses of
DNA sequence DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. Th ...
data of numerous ''Cyathus'' species has cast doubt on the validity of the morphology-based infrageneric classifications described by Brodie. This research suggests that ''Cyathus'' species can be grouped into three genetically related
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
s: ''ollum'' group: ''C. africanus'' (
type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * Ty ...
), ''C. africanus'' f. ''latisporus'', ''C. conlensoi'', ''C. griseocarpus'', ''C. guandishanensis'', ''C. hookeri'', ''C. jiayuguanensis'', '' C. olla'', ''C. olla'' f. ''anglicus'', and ''C. olla'' f. ''brodiensis''. ''striatum'' group: ''C. annulatus'', ''C. crassimurus'', '' C. helenae'', ''C. poeppigii'', ''C. renwei'', ''C. setosus'', '' C. stercoreus'', and ''C. triplex''. ''pallidum'' group: ''C. berkeleyanus'', ''C. olla'' f. ''lanatus'', ''C. gansuensis'', and ''C. pallidus''. This analysis shows that rather than fruit body structure,
spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...
size is generally a more reliable character for segregating species groups in ''Cyathus''. For example, species in the ''ollum'' clade all have spore lengths less than 15 µm, while all members of the ''pallidum'' group have lengths greater than 15 µm; the ''striatum'' group, however, cannot be distinguished from the ''pallidum'' group by spore size alone. Two characteristics are most suited for distinguishing members of the ''ollum'' group from the ''pallidum'' group: the thickness of the hair layer on the peridium surface, and the outline of the fruit bodies. The tomentum of ''Pallidum'' species is thick, like felt, and typically aggregates into clumps of shaggy or woolly hair. Their crucible-shaped fruit bodies do not have a clearly differentiated stipe. The exoperidium of ''Ollum'' species, in comparison, has a thin tomentum of fine hairs; fruit bodies are funnel-shaped and have either a constricted base or a distinct stipe.


Description

Species in the genus ''Cyathus'' have fruit bodies ( peridia) that are vase-, trumpet- or urn-shaped with dimensions of wide by tall. Fruit bodies are brown to gray-brown in color, and covered with small hair-like structures on the outer surface. Some species, like '' C. striatus'' and ''C. setosus'', have conspicuous bristles called setae on the rim of the cup. The fruit body is often expanded at the base into a solid rounded mass of
hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...
e called an emplacement, which typically becomes tangled and entwined with small fragments of the underlying growing surface, improving its stability and helping it from being knocked over by rain. Immature fruit bodies have a whitish membrane, an epiphragm, that covers the peridium opening when young, but eventually
dehisces Dehiscence is the splitting of a mature plant structure along a built-in line of weakness to release its contents. This is common among fruits, anthers and sporangia. Sometimes this involves the complete detachment of a part; structures that op ...
, breaking open during maturation. Viewed with a microscope, the peridium of ''Cyathus'' species is made of three distinct layers—the endo-, meso-, and ectoperidium, referring to the inner, middle, and outer layers respectively. While the surface of the ectoperidium in ''Cyathus'' is usually hairy, the endoperidial surface is smooth, and depending on the species, may have longitudinal grooves (striations). Because the basic fruit body structure in all
genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
of the family Nidulariaceae is essentially similar, ''Cyathus'' may be readily confused with species of ''
Nidula ''Nidula'' is a genus of fungi in the family Agaricaceae. Their fruit bodies resemble tiny egg-filled birds' nests, from which they derive their common name "bird's nest fungi". Originally described in 1902, the genus differs from the related gen ...
'' or '' Crucibulum'', especially older, weathered specimens of ''Cyathus'' that may have the hairy ectoperidium worn off. It distinguished from ''Nidula'' by the presence of a funiculus, a cord of hyphae attaching the peridiole to the endoperidium. ''Cyathus'' differs from genus ''Crucibulum'' by having a distinct three-layered wall and a more intricate funiculus.


Peridiole structure

Derived from the Greek word ''peridion'', meaning "small leather pouch", the peridiole is the "egg" of the bird's nest. It is a mass of
basidiospores A basidiospore is a reproductive spore produced by Basidiomycete fungi, a grouping that includes mushrooms, shelf fungi, rusts, and smuts. Basidiospores typically each contain one haploid nucleus that is the product of meiosis, and they are pro ...
and glebal tissue enclosed by a hard and waxy outer shell. The shape may be described as lenticular—like a
biconvex lens A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...
—and depending on the species, may range in color from whitish to grayish to black. The interior chamber of the peridiole contains a
hymenium The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in others some ...
that is made of basidia, sterile (non-reproductive) structures, and spores. In young, freshly opened fruit bodies, the peridioles lie in a clear gelatinous substance which soon dries. Peridioles are attached to the fruit body by a funiculus, a complex structure of hyphae that may be differentiated into three regions: the basal piece, which attaches it to the inner wall of the peridium, the middle piece, and an upper sheath, called the purse, connected to the lower surface of the peridiole. In the purse and middle piece is a coiled thread of interwoven hyphae called the funicular cord, attached at one end to the peridiole and at the other end to an entangled mass of hyphae called the hapteron. In some species the peridioles may be covered by a tunica, a thin white membrane (particularly evident in ''C. striatus'' and ''C. crassimurus''). Spores typically have an elliptical or roughly spherical shape, and are thick-walled,
hyaline A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none. Histopathology Hyaline cartilage is ...
or light yellow-brown in color, with dimensions of 5–15 by 5–8 
µm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...
.


Life cycle

The life cycle of the genus ''Cyathus'', which contains both
haploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...
and
diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...
stages, is typical of taxa in the basidiomycetes that can reproduce both asexually (via
vegetative Vegetative describes vegetation. Vegetative may also refer to: *Vegetative reproduction Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or cloning) is any form of asexual reproduction occurring in ...
spores), or sexually (with meiosis). Like other wood-decay fungi, this life cycle may be considered as two functionally different phases: the vegetative stage for the spread of mycelia, and the reproductive stage for the establishment of spore-producing structures, the fruit bodies. The vegetative stage encompasses those phases of the life cycle involved with the germination, spread, and survival of the mycelium. Spores germinate under suitable conditions of moisture and temperature, and grow into branching filaments called hyphae, pushing out like roots into the rotting wood. These hyphae are
homokaryotic Monokaryotic (adj.) is a term used to refer to multinucleate cells where all nuclei are genetically identical. In multinucleate cells, nuclei share one common cytoplasm, as is found in hyphal cells or mycelium of filamentous fungi. See also *Dika ...
, containing a single
nucleus Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom *Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucle ...
in each compartment; they increase in length by adding cell-wall material to a growing tip. As these tips expand and spread to produce new growing points, a network called the mycelium develops. Mycelial growth occurs by
mitosis In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is mainta ...
and the synthesis of hyphal biomass. When two homokaryotic hyphae of different mating compatibility groups fuse with one another, they form a
dikaryotic The dikaryon is a cell nucleus, nuclear feature which is unique to certain fungi. (The green alga ''Derbesia'' had been long considered an exception, until the heterokaryotic hypothesis was challenged by later studies.) Compatible cell-types can fus ...
mycelia in a process called plasmogamy. Prerequisites for mycelial survival and colonization a substrate (like rotting wood) include suitable humidity and nutrient availability. The majority of ''Cyathus'' species are saprobic, so mycelial growth in rotting wood is made possible by the secretion of enzymes that break down complex
polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wa ...
s (such as cellulose and
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...
) into simple sugars that can be used as nutrients. After a period of time and under the appropriate environmental conditions, the dikaryotic mycelia may enter the reproductive stage of the life cycle. Fruit body formation is influenced by external factors such as season (which affects temperature and air humidity), nutrients and light. As fruit bodies develop they produce peridioles containing the basidia upon which new basidiospores are made. Young basidia contain a pair of haploid sexually compatible nuclei which fuse, and the resulting diploid fusion nucleus undergoes meiosis to produce basidiospores, each containing a single haploid nucleus. The dikaryotic mycelia from which the fruit bodies are produced is long lasting, and will continue to produce successive generations of fruit bodies as long as the environmental conditions are favorable. The development of ''Cyathus'' fruit bodies has been studied in laboratory culture; ''C. stercoreus'' has been used most often for these studies due to the ease with which it may be grown experimentally. In 1958, E. Garnett first demonstrated that the development and form of the fruit bodies is at least partially dependent on the intensity of light it receives during development. For example, exposure of the
heterokaryotic A heterokaryon is a multinucleate cell that contains genetically different nuclei. Heterokaryotic and heterokaryosis are derived terms. This is a special type of syncytium. This can occur naturally, such as in the mycelium of fungi during sexual ...
mycelium to light is required for fruit to occur, and furthermore, this light needs to be at a wavelength of less than 530 nm. Continuous light is not required for fruit body development; after the mycelium has reached a certain stage of maturity, only a brief exposure to light is necessary, and fruit bodies will form if even subsequently kept in the dark. Lu suggested in 1965 that certain growing conditions—such as a shortage in available nutrients—shifts the fungus' metabolism to produce a hypothetical "photoreceptive precursor" that enables the growth of the fruit bodies to be stimulated and affected by light. The fungi is also positively
phototropic Phototropism is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light contain a hor ...
, that is, it will orient its fruit bodies in the direction of the light source. The time required to develop fruit bodies depends on a number of factors, such as the temperature, or the availability and type of nutrients, but in general "most species that do fruit in laboratory culture do so best at about 25 °C, in from 18 to 40 days."


Bioactive compounds

A number of species of ''Cyathus'' produce metabolites with biological activity, and novel chemical structures that are specific to this genus. For example,
cyathin ''Cyathus'' is a genus of fungi in the Nidulariaceae, a family collectively known as the bird's nest fungi. They are given this name since they resemble tiny bird's nests filled with "eggs", structures large enough to have been mistaken in ...
s are diterpenoid compounds produced by '' C. helenae'', ''C. africanus'' and ''C. earlei''. Several of the cyathins (especially cyathins B3 and C3), including striatin compounds from ''C. striatus'', show strong
antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
activity. Cyathane diterpenoids also stimulate
nerve growth factor Nerve growth factor (NGF) is a neurotrophic factor and neuropeptide primarily involved in the regulation of growth, maintenance, proliferation, and survival of certain target neurons. It is perhaps the prototypical growth factor, in that it was on ...
synthesis, and have the potential to be developed into therapeutic agents for neurodegenerative disorders such as
Alzheimer's disease Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term me ...
. Compounds named cyathuscavins, isolated from the mycelial
liquid culture A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture medium under controlled laboratory conditions. Microbial cultures are foundational and basic diagn ...
of ''C. stercoreus'', have significant
antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...
activity, as do the compounds known as cyathusals, also from ''C. stercoreus''. Various sesquiterpene compounds have also been identified in ''C. bulleri'', including cybrodol (derived from humulene), nidulol, and bullerone.


Distribution and habitat

Fruit bodies typically grow in clusters, and are found on dead or decaying wood, or on woody fragments in cow or horse dung. Dung-loving (coprophilous) species include '' C. stercoreus'', ''C. costatus'', ''C. fimicola'', and ''C. pygmaeus''. Some species have been collected on woody material like dead
herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of t ...
stems, the empty shells or
husk Husk (or hull) in botany is the outer shell or coating of a seed. In the United States, the term husk often refers to the leafy outer covering of an ear of maize (corn) as it grows on the plant. Literally, a husk or hull includes the protective ...
s of nuts, or on fibrous material like
coconut The coconut tree (''Cocos nucifera'') is a member of the palm tree family ( Arecaceae) and the only living species of the genus ''Cocos''. The term "coconut" (or the archaic "cocoanut") can refer to the whole coconut palm, the seed, or the ...
,
jute Jute is a long, soft, shiny bast fiber that can be spun into coarse, strong threads. It is produced from flowering plants in the genus ''Corchorus'', which is in the mallow family Malvaceae. The primary source of the fiber is ''Corchorus olit ...
, or
hemp Hemp, or industrial hemp, is a botanical class of ''Cannabis sativa'' cultivars grown specifically for industrial or medicinal use. It can be used to make a wide range of products. Along with bamboo, hemp is among the fastest growing plants o ...
fiber woven into matting, sacks or cloth. In nature, fruit bodies are usually found in moist, partly shaded sites, such as the edges of woods on trails, or around lighted openings in forests. They are less frequently found growing in dense vegetation and deep mosses, as these environments would interfere with the dispersal of peridioles by falling drops of water.Brodie (1975), p. 101. The appearance of fruit bodies is largely dependent upon features of the immediate growing environment; specifically, optimum conditions of temperature, moisture, and nutrient availability are more important factors for fruit rather than the broad geographical area in which the fungi are located, or the season. Examples of the ability of ''Cyathus'' to thrive in somewhat inhospitable environments are provided by ''C. striatus'' and ''C. stercoreus'', which can survive the drought and cold of winter in temperate North America, and the species '' C. helenae'', which has been found growing on dead alpine plants at an altitude of . In general, species of ''Cyathus'' have a worldwide
distribution Distribution may refer to: Mathematics *Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations * Probability distribution, the probability of a particular value or value range of a vari ...
, but are only rarely found in the arctic and
subarctic The subarctic zone is a region in the Northern Hemisphere immediately south of the true Arctic, north of humid continental regions and covering much of Alaska, Canada, Iceland, the north of Scandinavia, Siberia, and the Cairngorms. Generally, ...
.Brodie (1975), p. 150. One of the best known species, ''C. striatus'' has a circumpolar distribution and is commonly found throughout temperate locations, while the morphologically similar ''C. poeppigii'' is widely spread in tropical areas, rarely in the
subtropics The subtropical zones or subtropics are geographical and climate zones to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately 35° north and ...
, and never in temperate regions. The majority of species are native to warm climates. For example, although 20 different species have been reported from the United States and Canada, only 8 are commonly encountered; on the other hand, 25 species may be regularly found in the West Indies, and the
Hawaiian Islands The Hawaiian Islands ( haw, Nā Mokupuni o Hawai‘i) are an archipelago of eight major islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some from the island of Hawaii in the south to northernmost Kur ...
alone have 11 species.Brodie (1975), p. 117. Some species seem to be endemic to certain regions, such as ''C. novae-zeelandiae'' found in New Zealand, or ''C. crassimurus'', found only in Hawaii; however, this apparent endemism may just be a result of a lack of collections, rather than a difference in the habitat that constitutes a barrier to spread. Although widespread in the tropics and most of the temperate world, ''C. stercoreus'' is only rarely found in Europe; this has resulted in its appearance on a number of Red Lists. For example, it is considered endangered in Bulgaria, Denmark, and Montenegro, and "near threatened" in Great Britain. The discovery of a ''Cyathus'' species in
Dominican amber Dominican amber is amber from the Dominican Republic derived from resin of the extinct tree ''Hymenaea protera''. Dominican amber differentiates itself from Baltic amber by being nearly always transparent, and it has a higher number of fossil incl ...
('' C. dominicanus'') suggests that the basic form of the bird's nest fungi had already evolved by the Cretaceous era and that the group had diversified by the mid-
Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...
.


Ecology


Spore dispersal

Like other bird's nest fungi in the Nidulariaceae, species of ''Cyathus'' have their spores dispersed when water falls into the fruit body. The fruit body is shaped so that the kinetic energy of a fallen raindrop is redirected upward and slightly outward by the angle of the cup wall, which is consistently 70–75° with the horizontal. The action ejects the peridioles out of the so-called "splash cup", where it may break and spread the spores within, or be eaten and dispersed by animals after passing through the digestive tract. This method of spore dispersal in the Nidulariaceae was tested experimentally by George Willard Martin in 1924, and later elaborated by Arthur Henry Reginald Buller, who used ''C. striatus'' as the model species to experimentally investigate the phenomenon. Buller's major conclusions about spore dispersal were later summarized by his graduate student Harold J. Brodie, with whom he conducted several of these splash cup experiments:
Raindrops cause the peridioles of the Nidulariaceae to be thrown about four feet by splash action. In the genus ''Cyathus'', as a peridiole is jerked out of its cup, the funiculus is torn and this makes possible the expansion of a mass of adhesive hyphae (the hapteron) which clings to any object in the line of flight. The momentum of the peridiole causes a long cord to be pulled out of a sheath attached to the peridiole. The peridiole is checked in flight and the jerk causes the funicular cord to become wound around stems or entangled among plant hairs. Thus the peridiole becomes attached to vegetation and may be eaten subsequently by herbivorous animals.
Although it has not been shown experimentally if the spores can survive the passage through an animal's digestive tract, the regular presence of ''Cyathus'' on cow or horse manure strongly suggest that this is true. Alternatively, the hard outer casing of peridioles ejected from splash cups may simply disintegrate over time, eventually releasing the spores within.


Uses

Species in the family Nidulariaceae, including ''Cyathus'', are considered inedible, as (in Brodie's words) they are "not sufficiently large, fleshy, or odorous to be of interest to humans as food". However, there have not been reports of poisonous alkaloids or other substances considered toxic to humans. Brodie goes on to note that two ''Cyathus'' species have been used by native peoples as an aphrodisiac, or to stimulate fertility: ''C. limbatus'' in
Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...
, and ''C. microsporus'' in
Guadeloupe Guadeloupe (; ; gcf, label=Antillean Creole, Gwadloup, ) is an archipelago and overseas department and region of France in the Caribbean. It consists of six inhabited islands—Basse-Terre, Grande-Terre, Marie-Galante, La Désirade, and the ...
. Whether these species have any actual effect on human physiology is unknown.Brodie (1975), p. 120.


Biodegradation

Lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...
is a complex polymeric chemical compound that is a major constituent of wood. Resistant to biological decomposition, its presence in paper makes it weaker and more liable to discolor when exposed to light. The species ''C. bulleri'' contains three lignin-degrading enzymes:
lignin peroxidase In enzymology, a lignin peroxidase () is an enzyme that catalyzes the chemical reaction :1,2-bis(3,4-dimethoxyphenyl)propane-1,3-diol + H2O2 \rightleftharpoons 3,4-dimethoxybenzaldehyde + 1-(3,4-dimethoxyphenyl)ethane-1,2-diol + H2O Thus, the ...
, manganese peroxidase, and
laccase Laccases () are multicopper oxidases found in plants, fungi, and bacteria. Laccases oxidize a variety of phenolic substrates, performing one-electron oxidations, leading to crosslinking. For example, laccases play a role in the formation of lign ...
. These enzymes have potential applications not only in the
pulp and paper industry The pulp and paper industry comprises companies that use wood as raw material and produce pulp, paper, paperboard and other cellulose-based products. Manufacturing process The pulp is fed to a paper machine where it is formed as a paper web an ...
, but also to increase the digestibility and protein content of forage for cattle. Because laccases can break down
phenolic compounds In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of one or more hydroxyl groups (— O H) bonded directly to an aromatic hydrocarbon group. The simplest is phenol, . Phenolic compounds are c ...
they may be used to detoxify some environmental pollutants, such as
dye A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution an ...
s used in the textile industry. ''C. bulleri'' laccase has also been genetically engineered to be produced by '' Escherichia coli'', making it the first fungal laccase to be produced in a bacterial host. ''C. pallidus'' can biodegrade the explosive compound
RDX RDX (abbreviation of "Research Department eXplosive") or hexogen, among other names, is an organic compound with the formula (O2N2CH2)3. It is a white solid without smell or taste, widely used as an explosive. Chemically, it is classified as a n ...
(hexahydro-1,3,5-trinitro-1,3,5-triazine), suggesting it might be used to decontaminate
munition Ammunition (informally ammo) is the material fired, scattered, dropped, or detonated from any weapon or weapon system. Ammunition is both expendable weapons (e.g., bombs, missiles, grenades, land mines) and the component parts of other weapo ...
s-contaminated soils.


Agriculture

'' Cyathus olla'' has been investigated for its ability to accelerate the decomposition of stubble left in the field after harvest, effectively reducing pathogen populations and accelerating
nutrient cycling A nutrient cycle (or ecological recycling) is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cycli ...
through
mineralization Mineralization may refer to: * Mineralization (biology), when an inorganic substance precipitates in an organic matrix ** Biomineralization, a form of mineralization ** Mineralization of bone, an example of mineralization ** Mineralized tissues are ...
of essential plant nutrients.


Human biology

Various ''Cyathus'' species have antifungal activity against human pathogens such as ''
Aspergillus fumigatus ''Aspergillus fumigatus'' is a species of fungus in the genus ''Aspergillus'', and is one of the most common ''Aspergillus'' species to cause disease in individuals with an immunodeficiency. ''Aspergillus fumigatus'', a saprotroph widespread in ...
'', '' Candida albicans'' and '' Cryptococcus neoformans''. Extracts of ''C. striatus'' have inhibitory effects on NF-κB, a transcription factor responsible for regulating the expression of several genes involved in the immune system, inflammation, and cell death.


See also

* List of ''Cyathus'' species


References


Cited texts

* * *


External links


Trial field key to the species of BIRD'S NEST FUNGI in the Pacific Northwest
{{Taxonbar, from=Q1580329 Nidulariaceae Agaricales genera