Geastrum pectinatum
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''Geastrum pectinatum'' is an inedible species of mushroom belonging to the earthstar family of fungi. Although young specimens are spherical,
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 ...
development involves the outer layer of tissue splitting open like a star into 7 to 10 pointed rays that eventually bend back to point downward, revealing a small – broad – spore sac. The spore sac is supported by a small radially wrinkled stalk. There is a distinct conical opening (peristome) at the top of the spore sac that is up to long. It is commonly known as the beaked earthstar or the beret earthstar, in reference to the shape of the spore sac and its prominent, protruding peristome. The mass of spores and surrounding cells within the sac, the gleba, is dark-brown, and becomes powdery in mature specimens.
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 are spherical, measuring 4 to 6
micrometer Micrometer can mean: * Micrometer (device), used for accurate measurements by means of a calibrated screw * American spelling of micrometre The micrometre ( international spelling as used by the International Bureau of Weights and Measures; ...
s in diameter, with warts on their surfaces. Although uncommon, ''Geastrum pectinatum'' has a
cosmopolitan distribution In biogeography, cosmopolitan distribution is the term for the range of a taxon that extends across all or most of the world in appropriate habitats. Such a taxon, usually a species, is said to exhibit cosmopolitanism or cosmopolitism. The ext ...
, and has been collected in various locations in Europe, North and South America, Asia, Australia and Africa, where it grows on the ground in open woods. Like several other earthstars, crystals of
calcium oxalate Calcium oxalate (in archaic terminology, oxalate of lime) is a calcium salt of oxalic acid with the chemical formula . It forms hydrates , where ''n'' varies from 1 to 3. Anhydrous and all hydrated forms are colorless or white. The monohydrate ...
are found on ''G. pectinatum'', and are thought to be involved in fruit body maturation.


Taxonomy, classification, and naming

Christian Hendrik Persoon published the first description of ''Geastrum pectinatum'' in 1801. In 1860, Miles Joseph Berkeley and Moses Ashley Curtis described the species ''Geastrum biplicatum'' (originally named ''Geaster biplicatus''), based on specimens sent to them by Charles Wright that he obtained from the Bonin Islands during the North Pacific Exploring and Surveying Expedition. Japanese mycologist
Sanshi Imai was a Japanese mycologist of Hokkaido Imperial University. Eponymous taxa *'' Clitocybe imaiana'' *''Imaia ''Imaia'' is a fungal genus in the family Morchellaceae found in Japan, and in the Appalachian Mountains of the US. A monotypic genus ...
considered this identical with ''G. pectinatum'' in a 1936 publication. In 1959, mycologist J.T. Palmer reported comparing the original specimen collected by Persoon with fresh samples of what were then thought to be the distinct species ''G. plicatum'' and ''G. tenuipes'' (named by English naturalist Miles Joseph Berkeley in 1838 and 1848, respectively) and concluded the three specimens were
synonymous A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...
; the original Persoon specimen was then designated as the neotype. In Ponce de Leon's
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 ...
of '' Geastrum'', he placed the species in the
subgenus In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...
''Geastrum'', section ''Geastrum'', as the
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 ...
of the subsection ''Sulcostomata'', group Pectinatum. Other species in this group—characterized by a determinate peristome surrounded by a groove—are '' G. xerophilum'', and '' G. furfuraceum''. In Stanek's (1958) infrageneric concept, ''G. pectinatum'' is placed in section ''Perimyceliata'' (encompassing species whereby the mycelial layer covers the entire endoperidium), in subsection ''Glabrostomata'', which includes species with plicate peristomes. The
specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
is derived from the Latin ''pectinatum'', "like a comb". Its
common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...
s include the "beaked earthstar" or the "beret earthstar". Samuel Frederick Gray called it the "comblike shell-puff" in his 1821 "A Natural Arrangement of British Plants".


Description

Immature specimens – diameter – are roughly spherical and begin their development submerged in the ground, but gradually push above ground during maturation. In this state the outer surface is covered with mycelia, which forms a soft, fluffy coat that holds soil and debris to the outer surface. The young fruit bodies often have a rounded knob or protuberance. Like other members of genus '' Geastrum'', ''G. pectinatum'' has a
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 ...
wall that is multilayered. At maturity, the outer layer (the exoperidium) splits open from the top in a stellate (star-shaped) manner into 7–9 rays that support the spore sac contained within the inner wall (the endoperidium). The expanded specimens are up to broad and tall. The rays of the exoperidium bend back (reflex), simultaneously elevating the spore sac above the ground in what is known as the ''fornicate'' condition; this position exposes the spore sac to more air currents, aiding spore dispersal. The surface of the rays often crack to reveal lighter-colored areas, especially along the edges. Together with a well-developed layer of mycelium, the rays are typically bound to fragments of earth or forest duff. The tough and membranous endoperidium comprising the spore sac, purple-brown in color and tall by wide, is supported by a small stalk—a pedicel—that is 3–4 mm long by 7–10 mm wide and which has a grooved (sulcate) apophysis, or swelling. This ring-shaped swelling is made of remnants from a tissue called the pseudoparenchymatous layer. When fresh, the pseudoparenchymatous layer is whitish in color, thick and fleshy; it dries to become brown to dark brown while shrinking and often splitting and peeling. The endoperidium may be
pruinose Pruinescence , or pruinosity, is a "frosted" or dusty-looking coating on top of a surface. It may also be called a pruina (plural: ''pruinae''), from the Latin word for hoarfrost. The adjectival form is pruinose . Entomology In insects, a "blo ...
—covered with fine, white, powder—although the presence of this characteristic has been noted as being somewhat variable. The spore sac is opened by a single apical pore atop a conical "beak", or peristome. The peristome is ''pectinate''—made of tissue that resembles the teeth of a comb; the
specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
is named after this characteristic. The peristome is long, and comprises 20–32 distinct ridges. The mass of spores and surrounding cells within the sac, the gleba, is dark-brown, and becomes powdery in mature specimens. Internally, the endoperidium contains a structure called the ''columella'' that is narrowly conical in shape, whitish or pale brown, and extends more than halfway into the gleba. ''G. pectinatum'' has no distinguishable odor or taste; like other earthstar mushrooms, it is inedible, and of "no alimentary interest".


Microscopic characteristics

The
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 of ''G. pectinatum'' are brown and opaque. They have a roughly spherical shape and are ornamented with transparent (
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 ...
), truncate warts; the diameter is 4–4.5 
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 ...
, or 5.5–6.5 if the lengths of the warts is included. Spore-bearing cells, the basidia, are 2- or 4-spored, while cystidia (specialized sterile cells that occur at the
hymenial 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 c ...
surface in some mushrooms) are absent. The capillitia—a mass of thread-like sterile fibers dispersed among the spores—are light brown and 3–7 µm in diameter. They are tapered, thick-walled with a narrow interior, and either smooth or slightly encrusted.


Similar species

''Geastrum pectinatum'' has been mistaken for the morphologically similar but smaller species '' G. schmidelii''. The latter species lacks vertical striations on the basal portions of the endoperidium, and does not have a pseudoparenchymatous collar around the stem. Another similar species, '' G. berkeleyi'', has a shorter stem and is missing the ridges at the base of the spore sac. Further, the color of its spore sac is usually brown, in contrast to the gray-blue of ''G. pectinatum''. '' G. xerophilum'' also has a dusting of white powder on the surface of the spore sac, but unlike ''G. pectinatum'', consistently lacks a ring at the base of the pedicel; furthermore, in contrast to ''G. pectinatum'', the spores of ''G. xerophilum'' are yellow and contain oil drops that are readily observable with a microscope. '' G. striatum'' has smaller fruit bodies than ''G. pectinatum'', and a distinct collar-like apophysis.


Distribution and habitat

This species has been reported to grow solitary or in groups on sandy soil or rich composted soil in both mixed and
coniferous Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All extant ...
forests, often beneath cedars. In Hawaii, it is usually found growing in
duff Duff may refer to: People * Duff (surname) * Duff (given name) * Duff (nickname) * Karen Duffy, an actress, model, and former MTV VJ once known as "Duff" * Duff Roman, on-air name of Canadian radio personality and executive David Mostoway (bo ...
under coastal '' Casuarina'' and groves of ''
Cupressus ''Cupressus'' is one of several genera of evergreen conifers within the family Cupressaceae that have the common name cypress; for the others, see cypress. It is considered a polyphyletic group. Based on genetic and morphological analysis, the ge ...
''. The species has been noted to occur in late summer and autumn (in Britain and Europe), but the fruit bodies may dry and persist for some time. ''Geastrum pectinatum'' has a
cosmopolitan distribution In biogeography, cosmopolitan distribution is the term for the range of a taxon that extends across all or most of the world in appropriate habitats. Such a taxon, usually a species, is said to exhibit cosmopolitanism or cosmopolitism. The ext ...
. It has been reported from Australia, and New Zealand, Africa (the Congo, South Africa) Central America (Costa Rica), Asia (Northeastern China and Japan), and South America (Brazil). In Europe, it has been reported from Belgium, Ireland, Germany, the Netherlands, Norway, and Sweden. In the Middle East, it has been recorded in Israel, and Turkey. In North America, it is known from the United States (including Hawaii), Canada, and Mexico. It is in the
Red Data Book The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...
(documenting rare and endangered species) of Latvia, and is considered a threatened species in Poland. North American sources gives its frequency of appearance as "rare", but Stellan Sunhede, in his 1989
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 ...
on the Geastraceae, considers it one of the most common earthstar mushrooms of northern Europe.Sunhede (1898), p. 294.


Calcium oxalate crystals

Calcium oxalate Calcium oxalate (in archaic terminology, oxalate of lime) is a calcium salt of oxalic acid with the chemical formula . It forms hydrates , where ''n'' varies from 1 to 3. Anhydrous and all hydrated forms are colorless or white. The monohydrate ...
is a common crystalline compound found in many fungi, including the earthstars. The presence of calcium oxalate crystals—apparent as a whitish powder on the surface of the spore sac—has been verified for ''G. pectinatum'' using scanning electron microscopy. The calcium oxalate crystals occur in the tetragonal form, known as
weddellite Weddellite ( Ca C2 O4·2 H2O) is a mineral form of calcium oxalate named for occurrences of millimeter-sized crystals found in bottom sediments of the Weddell Sea, off Antarctica. Occasionally, weddellite partially dehydrates to whewellite, formi ...
. A study on the related species '' Geastrum saccatum'' has shown that these crystals are responsible for the characteristic opening ( dehiscence) of the outer peridial layers. The formation of calcium oxalate crystals stretches the layers of the outer walls, pushing apart the inner and outer layers of the peridium.


References


Cited literature

*


External links


botany.cz
''Geastrum pectinatum'' Pers. – hvězdovka dlouhokrká / hviezdovka dlhokŕčková (in Czech) {{DEFAULTSORT:Geastrum Pectinatum pectinatum Fungi described in 1801 Fungi of Asia Fungi of Africa Fungi of Australia Fungi of Europe Fungi of New Zealand Fungi of Central America Fungi of North America Fungi of South America Inedible fungi Fungi of Oceania Taxa named by Christiaan Hendrik Persoon Fungi without expected TNC conservation status