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Cyathus striatus
Cyathus striatus
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Cyathus striatus
Scientific classification Edit this classification
Kingdom: Fungi
Division: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Nidulariaceae
Genus: Cyathus
Species:
C. striatus
Binomial name
Cyathus striatus
(Huds.) Willd. (1787)
Synonyms[4]
  • Peziza striata Huds. (1778)
  • Nidularia striata (Huds.) With. (1792)[1]
  • Cyathella striata (Huds.) Brot. (1804)[2]
  • Nidularia striata var. pusilla Berk. (1839)[3]
Cyathus striatus
Mycological characteristics
Glebal hymenium
Cap is infundibuliform
Hymenium attachment is not applicable
Lacks a stipe
Ecology is saprotrophic
Edibility is inedible

Cyathus striatus, commonly known as the fluted bird's nest,[5][6] is a common saprobic bird's nest fungus.

This fungus resembles a miniature bird's nest with numerous tiny "eggs"; the eggs, or peridioles, are actually lens-shaped bodies that contain spores. The color and size of this species can vary somewhat, but they are typically less than a centimeter wide and tall, and grey or brown in color. The common name splash cups alludes to the method of spore dispersal: the sides of the cup are angled such that falling drops of water can dislodge the peridioles and eject them from the cup.[7][8] C. striatus can be distinguished from most other bird's nest fungi by its hairy exterior and grooved (striated) inner walls.

Although most frequently found growing on dead wood in open forests, it also grows on wood chip mulch in urban areas. The fruiting bodies are encountered from summer until early winter. with a widespread distribution throughout temperate regions of the world.

Taxonomy

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Cyathus striatus was first described by William Hudson in his 1778 work Flora Anglica as Peziza striata.[9] Carl Ludwig Willdenow transferred it to Cyathus in 1787.[10] The specific epithet is derived from the Latin stria, meaning "with fine ridges or grooves",[11] refers to the grooves inside the cups.[12]

Description

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a) young and mature fruiting bodies in longitudinal section; (b), (c) single peridioles–entire, and in section[13]

The "nest", or peridium, is usually about 7 to 10 mm in height and 6 to 8 mm in width,[8] but the size is somewhat variable and specimens have been found with heights and widths of up to 1.5 cm (58 in).[7] The shape typically resembles a vase or inverted cone. The outer surface (exoperidium) ranges in color from slightly brownish to grayish buff to deep brown; the exoperidium has a shaggy or hairy texture (a tomentum), with the hairs mostly pointing downward. The inner surface of the peridium (the endoperidium) is striated or grooved, and shiny. Young specimens have a lid, technically called an epiphragm, a thin membrane that covers the cup opening. The epiphragm is hairy like the rest of the exoperidial surface, but the hairs often wear off leaving behind a thin white layer stretched across the lid of the cup. As the peridium matures and expands, this membrane breaks and falls off, exposing the peridioles within.[14] The peridium is attached to its growing surface by a mass of closely packed hyphae called an emplacement; in C. striatus the maximum diameter of the emplacement is typically 8–12 mm, and often incorporating small fragments of the growing surface into its structure.[15] The species is inedible.[16]

Peridiole structure

The peridioles are about 1 to 1.5 mm wide and rarely up to 2 mm wide. They are disc-shaped, but may appear angular due to pressure from neighbouring peridioles. Peridioles may be dark, or a drab gray if still covered with a thin membrane called a tunica.[17]

A peridiole and attached funiculus in cross-section

Peridioles in C. striatus are sheathed and attached to the endoperidium by complex cords of mycelia known as a funiculus in the singular. The funiculus is 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. Inside 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. When dry the funiculus is brittle, but when wet it is capable of long extension.[14]

Microscopic characteristics

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The basidia, the spore-bearing cells, are club-shaped with long stalks. They typically hold 4 spores that are sessile, that is, attached directly to the surface of the basidium, rather than by a short stalk (a sterigmata).[18] Spores measure about 15 to 20 μm long by 8 to 12 μm wide. They are elliptical, smooth, hyaline, and notched at one end.[7][8] During development, the spores are separated from the basidia when the latter collapse and gelatinize along with other cells lining the inner walls of the peridiole. The spores expand in size somewhat after being detached from the basidia.[18]

Life cycle

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The outer surface of C. striatus is covered with a shaggy or woolly tomentum.

Cyathus striatus can reproduce both asexually (via vegetative spores), or sexually (with meiosis), typical of taxa in the basidiomycetes that contain both haploid and diploid stages. Basidiospores produced in the peridioles each contain a single haploid nucleus. After the spores have been dispersed into a suitable growing environment, they germinate and develop into homokaryotic hyphae, with a single nucleus in each cell compartment. When two homokaryotic hyphae of different mating compatibility groups fuse with one another, they form a dikaryotic mycelia in a process called plasmogamy. After a period of time and under the appropriate environmental conditions, fruiting bodies may be formed from the dikaryotic mycelia. These fruiting bodies produce peridioles containing the basidia upon which new spores are made. Young basidia contain a pair of haploid sexually compatible nuclei which fuse, and the resulting diploid fusion nucleus undergoes meiosis to produce haploid basidiospores.[19] The process of meiosis in C. striatus has been found to be similar to that of higher organisms.[20]

Spore dispersal

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The cone shaped fruiting body of Cyathus striatus makes use of a splash-cup mechanism to help disperse the spores. When a raindrop hits the interior of the cup with the optimal angle and velocity, the downward force of the water ejects the peridioles into the air. The force of ejection rips open the funiculus, releasing the tightly wound funicular cord. The hapteron attached to the end of the funiculus is adhesive, and when it contacts a nearby plant stem or stick, the hapteron sticks to it; the funicular cord wraps around the stem or stick powered by the force of the still-moving peridiole (similar to a tetherball). The peridioles degrade over time to eventually release the spores within, or they may be eaten by herbivorous animals and redeposited after passing through the digestive tract.[21]

Similar species

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Cyathus stercoreus is similar, but grows in dung and its cups are not grooved.[12]

Habitat and distribution

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Cyathus striatus is a saprobic fungus, deriving its nutrition from decaying organic material, and is typically found growing in clusters on small twigs or other woody debris. It is also common on mulch under shrubs.[22] The features of the microenvironment largely influence the appearance of C. striatus; all else being equal, it is more likely to be found in moist, shallow depressions than elevated areas.[23] It is very widespread in temperate areas throughout the world,[17] growing in summer and fall.[24] The fungus has been recorded from Asia, Europe, North America, Central America, South America, and New Zealand.[25]

Bioactive compounds

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Cyathus striatus has proven to be a rich source of bioactive chemical compounds. It was first reported in 1971 to produce "indolic" substances (compounds with an indole ring structure) as well as a complex of diterpenoid antibiotic compounds collectively known as cyathins.[26][27] Several years later, research revealed the indolic substances to be compounds now known as striatins. Striatins (A, B and C) have antibiotic activity against fungi imperfecti, and various Gram-positive and Gram-negative bacteria.[28] C. striatus also produces sesquiterpene compounds called schizandronols.[29] It also contains the triterpene compounds glochidone, glochidonol, glochidiol and glochidiol diacetate, cyathic acid, striatic acid, cyathadonic acid and epistriatic acid.[30] The latter four compounds were unknown prior to their isolation from C. striatus.

See also

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References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia
from Grokipedia
Cyathus striatus, commonly known as the fluted bird's nest fungus, is a saprobic basidiomycete fungus in the family Nidulariaceae, characterized by its small, cup-shaped fruiting bodies that mimic tiny bird's nests filled with lens-shaped "eggs" called peridioles. These fruiting bodies typically measure 6–15 mm tall and 6–10 mm wide, with a shaggy, hairy outer surface ranging from grayish buff to dark brown and a shiny, grooved (fluted) inner surface. The peridioles, which are silvery and 1–2 mm across, contain up to 30 million spores each and are attached to the nest's interior by thread-like funiculi for dispersal. First described as Peziza striata by William Hudson in 1778 and later reclassified into the genus by Christian Hendrik Persoon in 1801, C. striatus belongs to the order within the phylum and class . It is distinguished from similar species like by its striated inner walls, smaller ellipsoid spores (15–20 × 8–12 µm) that are smooth and thick-walled, and its preference for woody substrates over dung. Young fruitbodies are covered by a thin white that ruptures to reveal the peridioles as they mature. Ecologically, C. striatus plays a role in as a saprotroph, breaking down such as decaying wood, forest litter, and wood chips, often in clusters on softwoods in open s, woodland edges, or disturbed urban areas like gardens and beds. Its spores are primarily dispersed through raindrop impact, which ejects the peridioles up to 1 meter away, or via animal consumption and subsequent . Fruiting occurs year-round but peaks from summer to fall (May–November in temperate zones), making it inconspicuous yet widespread. With a global distribution across temperate and subtropical regions—including , , , and parts of the C. striatus is one of the most common bird's nest fungi, though it is inedible and poses no known to humans or . Its adaptability to both natural woodlands and human-modified landscapes highlights its ecological versatility in nutrient recycling.

Taxonomy and Classification

Etymology and Synonyms

The genus name Cyathus derives from kyathos, meaning "cup" or "ladle," alluding to the cup-shaped fruiting bodies characteristic of the genus. The specific striatus comes from the Latin striatus, meaning "grooved" or "furrowed," referring to the prominent longitudinal ridges on the inner surface of the fruiting body. Cyathus striatus was first described as Peziza striata by William Hudson in his 1778 work Flora Anglica, based on specimens from Britain. In 1787, Carl Ludwig Willdenow transferred the species to the genus Cyathus in Florae Berolinensis Prodromus, establishing the currently accepted name Cyathus striatus (Huds.) Willd., which was later sanctioned by Christian Hendrik Persoon. Historical synonyms include:
  • Peziza striata Huds. (1778), the basionym.
  • Nidularia striata (Willd.) With. (1792).
  • Cyathella striata (Willd.) Brot. (1804).
This nomenclatural history reflects early classifications of bird's nest fungi within the family, initially lumped with cup fungi like before recognition of their distinct morphology in the late .

Phylogenetic Position

Cyathus striatus is the of the , which is classified within the family , order , class , and phylum . This placement reflects the saprotrophic bird's nest fungi's position among the , supported by molecular evidence from sequences. The encompasses over 50 worldwide, with C. striatus serving as a key reference in phylogenetic studies due to its morphological variability and widespread distribution. Analyses using (ITS) and large subunit (LSU) rDNA sequences have confirmed the of , positioning C. striatus within the striatum supergroup, which includes several closely related clades, such as the stercoreus subgroup with like C. stercoreus. Recent systematic updates, including a 2023 molecular review, have refined the internal phylogeny of using expanded sampling of 39 species and markers like ITS and LSU, confirming C. striatus's placement and suggesting potential cryptic diversity within the species. Earlier studies from 2007, using ITS and LSU rDNA sequences, have confirmed the of and proposed infrageneric groupings such as the striatum group. The genus is distinguished from related genera like Crucibulum by molecular and morphological differences, including peridioles and fruitbody structure, as shown in broader phylogenetic analyses. These analyses, including recent phylogenomic studies as of 2024, underscore Nidulariaceae's sister relationship to Squamanitaceae within .

Morphology

Macroscopic Features

_Cyathus striatus produces vase- or funnel-shaped fruitbodies known as peridia, typically measuring 6–15 mm in height and 6–10 mm in width at the mouth. The overall structure resembles a miniature bird's nest, with a short, indistinct base that flares outward toward the rim. These fruitbodies often occur in clusters on decaying or , enhancing their inconspicuous appearance in natural settings. The exterior surface of the peridium is covered in fine, shaggy, or woolly hairs, giving it a tomentose texture that ranges from grayish-brown to reddish-brown in color. In young specimens, the fruitbody is initially enclosed by a , membranous lid () that splits open upon maturity, revealing the interior. As they age, colors may darken to dull gray or brown, with the hairy exterior becoming more pronounced. The interior of the peridium is smooth and shiny, featuring 20–30 prominent longitudinal ridges or striations that give it a fluted appearance. At the base, 4–10 disc- or lens-shaped peridioles, resembling small "eggs," are attached by thread-like cords to the inner wall; these measure 1–2.5 mm in diameter and are typically dark gray to black.

Microscopic Characteristics

The basidiospores of Cyathus striatus are to elliptical, smooth-walled, and to subhyaline, measuring 13.5–20 × 8–12 μm, with a distinct apiculus at the basal end and walls typically 2–3 μm thick. These spores are inamyloid, showing no reaction to Melzer's reagent, and they continue to expand slightly after detachment from the basidia. The basidia are clavate, irregularly scattered within the of the peridioles, and typically 4-spored, bearing sessile basidiospores directly on short sterigmata. The peridium exhibits a distinctive three-layered structure under . The outer layer (ectoperidium) consists of plicate, tomentose hyphae that are to pale brown and 4.7–5.8 μm wide, forming a hairy surface. The middle layer (mesoperidium) is composed of to pale brown hyphae in a textura intricata arrangement, 2.6–2.8 μm wide, providing structural support. The inner layer (endoperidium) features gray to brown, epidermoid cells that create a shiny, striated surface. Overall, the peridium thickness exceeds 160 μm, with no reactions observed in hyphal components. The funiculus, which anchors peridioles to the peridium, comprises pale yellowish, aseptate mycelial cords 4–5 μm wide that branch irregularly and extend from a basal attachment point to envelop the peridioles in a sheath-like structure. This complex includes a basal piece securing it to the endoperidium, a main cord, and a purse or elastic sheath that aids in peridiole ejection and .

Reproduction and Ecology

Life Cycle

The life cycle of Cyathus striatus follows the typical pattern of basidiomycetes, commencing with the of haploid basidiospores released from mature peridioles. These spores germinate under optimal conditions of moisture and moderate temperatures, producing germ tubes that elongate into uninucleate hyphae forming a primary . This haploid phase allows the to colonize decaying wood or organic substrates, with hyphal growth rates varying based on environmental factors. Reproduction is primarily sexual, as C. striatus is heterothallic and tetrapolar, featuring multiple (four at the MAT-A locus and five at the MAT-B locus among sampled isolates) that necessitate between compatible hyphae. Fusion of compatible results in a dikaryotic secondary , identifiable by the presence of clamp connections at hyphal , which supports further vegetative growth and eventual fruiting. Rare reports indicate potential via vegetative spores, though no chlamydospores or oidia have been consistently observed in closely related species. Environmental triggers, particularly increased moisture and suitable temperatures around 20–25°C, initiate primordia formation on the secondary . Fruitbody development proceeds with the initial formation of the peridium, a cup-shaped outer wall initially covered by a thin membrane that ruptures to expose the interior. Peridioles, lens-shaped structures enclosing clusters of basidia, then develop within the peridium, maturing as the fruitbody expands and the striations become prominent. Under laboratory conditions optimal for related Cyathus species, fruitbodies fully mature in approximately two weeks, completing the cycle from spore germination to spore-producing nest in several weeks overall.

Spore Dispersal

_Cyathus striatus employs a splash-cup mechanism for spore dispersal, where raindrops striking the interior of the cup-shaped fruitbody eject lens-shaped peridioles containing . These peridioles are propelled at speeds ranging from 1.7 to 5.5 m/s, with a mean of 3.6 m/s, utilizing less than 2% of the incoming raindrop's . The ejection occurs rapidly, often within 10 milliseconds, as raindrops impact the cup's rim, generating sufficient force to dislodge and launch the peridioles. Each peridiole features a tough, gelatinous outer that encases approximately 2 million basidiospores, providing protection during ejection and flight. Attached to the peridioles is a coiled cord ending in a sticky hapteron, which remains condensed during dispersal but unravels upon impact, stretching up to 12 cm to tether the peridiole to or other substrates. Upon landing and subsequent drying, the peridiole wall ruptures, releasing the basidiospores for on suitable . The fluted cup shape of C. striatus, characterized by longitudinal ridges on the inner surface, optimizes ejection efficiency by breaking up water pools and enhancing upon raindrop impact, directing force more effectively than smoother cups in related . This results in primarily short-distance dispersal, with peridioles traveling up to 1 m horizontally and 0.5 m vertically, promoting clustering around the parent fruitbody. Such localized spread aids in colonizing nearby decaying wood or herbaceous debris, while the tethering mechanism positions peridioles for potential ingestion by herbivores, further extending dispersal via endozoochory.

Habitat and Distribution

Cyathus striatus is a saprobic that plays a key role as a , breaking down decaying in various ecosystems. It primarily colonizes dead and materials, including wood chips, stumps, branches, and leaf litter, where it facilitates nutrient recycling. The fungus often grows in dense clusters on these substrates, contributing to the process in forest floors and disturbed sites. This species exhibits a cosmopolitan distribution, with widespread occurrence in temperate zones across multiple continents. It is commonly reported in Europe, North America, and Asia, including a notable 2021 record from Arunachal Pradesh, India, on decaying bamboo stumps and a 2025 record from Mandla, Madhya Pradesh, India. Populations are also documented in Australasia, such as New Zealand, highlighting its adaptability to diverse temperate environments. In the , fruiting bodies typically appear from summer through early winter, aligning with periods of moderate moisture and temperature. C. striatus thrives in edges, gardens, and urban landscapes, particularly where or woody debris is present, allowing it to persist in both natural and human-modified habitats.

Chemical Properties and Applications

Bioactive Compounds

Cyathus striatus produces a variety of bioactive secondary metabolites, primarily diterpenoids, sesquiterpenes, and triterpenes, isolated mainly from mycelial cultures and fruitbodies. These compounds contribute to the fungus's and have demonstrated and other biological activities. Extraction typically involves solvent-based methods, such as methanol-acetone for or for fruitbodies, followed by chromatographic purification like or LH-20. Among the diterpenoids, the striatins represent early-discovered examples, with striatins A, B, and C first isolated in 1977 from submerged cultures of C. striatus . These cyathane-type diterpenoid glycosides feature a cyathane skeleton linked to a unit, with molecular formulas C₂₇H₃₆O₇ (striatin A), C₂₇H₃₈O₈ (striatin B), and C₂₅H₃₄O₇ (striatin C); they exhibit antibiotic activity against (MIC 0.2–20 µg/mL) and imperfect fungi, inhibiting protein and RNA synthesis in sensitive strains like Bacillus brevis. The broader cyathins, including cyathion and striatin variants, share this skeleton and show antifungal and antibacterial effects, with cyathin initially reported from related species but confirmed in C. striatus extracts. Post-2010 studies have expanded this class, isolating striatoids A–F in 2015 from mycelial cultures, which are highly oxygenated polycyclic cyathane-xylosides with neurotrophic potential via stimulation, alongside antibacterial activities. Further, pyristriatins A and B, novel cyathane diterpenoids, were reported in 2016 from cultures, displaying moderate antibacterial, , and antitumor properties. Sesquiterpenes in C. striatus include schizandronols, isolated in 1982 from aerated liquid cultures, identified as oxygenated cadinane derivatives like schizandronol (a keto alcohol) based on spectral analysis including NMR and . These compounds represent the first fungal isolation of schizandronol, previously known from sources, and exhibit potential cytotoxic effects in preliminary screenings of fungal metabolites. Triterpenes such as glochidone, glochidonol, and glochidiol were isolated in 1986 from fruitbodies of C. striatus, featuring lupane skeletons with keto or hydroxyl groups. Cyathic , a related triterpenoid , has also been identified in C. striatus, contributing to the fungus's diverse profile, though specific activities for this variant remain less characterized beyond general contexts.

Biological and Medicinal Potential

Cyathus striatus exhibits notable activity, particularly against plant pathogenic bacteria and fungi, positioning it as a potential biocontrol agent in . A study demonstrated that extracts from C. striatus effectively inhibited the growth of plant pathogens such as Pectobacterium spp., Pseudomonas spp., , and , as well as fungal species like Fusarium spp., with inhibition zones comparable to commercial fungicides in assays. This efficacy stems from secondary metabolites like striatins A, B, and C, which display effects against Gram-positive and , as well as imperfect fungi, at concentrations as low as 10-50 μg/mL. In medicinal contexts, compounds from C. striatus, including cyathane diterpenoids such as striatins, show properties alongside and neurotrophic effects that support applications. These diterpenoids promote synthesis, aiding neuronal regeneration in damaged tissues, as observed in cell-based assays where they enhanced neurite outgrowth by up to 200% at non-toxic doses. extracts have also induced in human cells via activation and reduced xenograft tumor growth in mice by 40-60%, highlighting anticancer potential, though primarily through and preclinical models. Beyond antimicrobials, C. striatus produces -degrading enzymes with biotechnological promise, including manganese peroxidases that depolymerize in the presence of Mn²⁺, enabling applications in biofuel production and . No human toxicity has been reported for C. striatus or its extracts, with studies confirming the absence of pathogenic effects or poisonous alkaloids in mammalian models. Research on C. striatus remains limited by a focus on and animal studies, with no clinical trials conducted as of 2025 to validate therapeutic efficacy in humans. A 2023 review on bird's nest fungi emphasized the need for integrated phylogenetic studies to preserve , linking taxonomic clarity to sustained bioactive compound discovery and conservation strategies.

References

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