Tuber oregonense
Encyclopedia
Tuber oregonense, commonly known as the Oregon white truffle, is a species of edible truffle in the genus Tuber
. Described as new to science in 2010, the North American species is found on the western coast of the United States, from northern California
to southern British Columbia
west of the Cascade Range
. A mycorrhiza
l fungus, it grows a symbiotic association with Douglas fir. It overlaps in distribution with the closely related T. gibbosum
, but they have different growing seasons: T. oregonense typically appears from October through March, while T. gibbosum grows from January to June. The fruit bodies
of the fungus are roughly spherical to irregular in shape, and resemble small potatoes up to 5 cm (2 in) in diameter. Inside the truffle is the gleba
, which is initially white before it becomes a marbled tan
color. The large, often thick-walled, and strongly ornamented spore
s are produced in large spherical asci
. The truffle is highly prized for its taste and aroma. Attempts to cultivate the truffles in Christmas tree farms
have been successful.
and named in a 2010 Mycologia
publication, although Tuber oregonense had previously been used as a provisional name (as Tuber oregonense Trappe & Bonito) in a number of field guide
s and other popular publications for several years. The type specimen was collected from Benton County, Oregon
on 3 February, 2007 along U.S. Route 20 in Oregon
.
The specific epithet oregonense derives from the name Oregon
and the Latin
suffix -ense (relating to), in reference to western Oregon being its central region of abundance. The fungus is commonly
known as the Oregon white truffle. Truffle authority James Trappe was initially intending to name the species as a variety of Tuber gibbosum (i.e., as Tuber gibbosum var. oregonense) before molecular analysis revealed that it was clearly genetically distinct enough to warrant being designated a separate species.
T. oregonense is part of the Gibbosum clade
of the genus Tuber
. Species in this clade have "peculiar wall thickenings on hyphal tips emerging from the peridial surface at maturity."
, as the truffle matures it develops red to reddish-brown or orangish-brown patches; with age it becomes orange-brown to reddish-brown overall and often develops cracks on the surface. The peridium is 0.2–0.4 mm thick, and the surface texture ranges from relatively smooth to covered with tiny "hairs" that are more dense in the furrows, and more scattered on the exposed lobes. The gleba
is solid, in youth the fertile tissue is whitish and marbled with mostly narrow, white, hypha
-stuffed veins that emerge throughout the peridium to its surface. In maturity, the fertile tissue is light brown to brown from the color of the spores, but the marbling veins remain white. The odor and flavor of the flesh are mild in youth, but soon become strong, pungent and complex, or "truffly".
The spore
s are ellipsoid to somewhat spindle-shaped with narrowed ends, and light brownish in color. The size of the spores varies depending upon the type of asci in which they develop: in one-spored asci
they measure 42.5–62.5 by 17.5–30 µm; in two-spored asci they are 32.5–50 by 15–25 µm; in three-spored asci they are 27.5–45 by 15–25 µm; in four-spored asci they are 25–38.5 by 13–28 µm; in five-spored asci 28–34 by 22–25 µm (all sizes excluding surface ornamentation). The spore walls are 2–3 µm thick and are covered with a honeycomb-like (alveolate) network. The cavities of the honeycomb typically have five or six sides, and the corners form spines that are 5–7 µm tall by 0.5 µm thick. A "microreticulum" appears in some spores when the light microscope objective
is focused on the optical cross section but not on the spore wall surface, or on scanning electron microscopy micrographs of the surface. Young asci range in shape from spherical to broadly ellipsoid to ovoid (egg-shaped) or pyriform (pear-shaped); sometimes the base of the ascus is narrowed like a stipe
,and measures up to 15 by 7 µm. Mature asci are spherical to broadly ellipsoid or misshapen from the pressure of crowded spores within. They are hyaline
(translucent), thin-walled, 60–85 by 65–75 µm, 1–4-(occasionally 5)-spored, and astipitate (without a stipe) at maturity.
The peridiopellis (the cuticle of the peridium) is 200–300 µm thick plus or minus 80 µm of tightly interwoven hypha
e that are 3–5 (sometimes up to 10) µm broad. The cells are short and have nearly hyaline walls that measure 0.5–1 µm thick; the interior veins emerge through the peridium the cells and often form a localized tissue of rounded cells up to 12 µm broad. The degree to which the surface is covered with fine "hairs" is variable; these hairs are made of tangled hyphae and emergent thin-walled hyphal tips 2–5 µm in diameter, some even and smooth, some with granulated
surfaces and some with moniliform walls (resembling a string of beads) that are irregularly thickened by hyaline bands that are 0.5–2 µm wide. The subpellis (the tissue layer immediately under the pellis) is abruptly differentiated from the pellis, 150–220 µm thick, and comprises interwoven, nearly hyaline, thin-walled hyphae 2–10 µm wide with scattered cells up to 15 µm wide. The gleba is made of hyaline, thin-walled, interwoven hyphae that are 2–7 µm broad with scattered cells that are inflated up to 15 µm.
species. Its odor has been described as ""truffly", a complex of garlic, spices, cheese, and "indefinable other essences"; the fungus is prized after by commercial truffle harvesters and consumers for its intense fragrance. Because they grow in the topsoil and needles, they are considered to have a more "floral" and "herbal" flavor profile than related European truffles. Some individuals have had success in growing the truffles in Christmas tree farms in Oregon. The species has been commercially harvested in the Pacific Northwest since the 1980s. The Oregon Truffle Festival has been held in Eugene
yearly since 2006 to coincide with the maturing of the truffle in late January; it features activities such as cultivation seminars, truffle hunting excursions, winery tours, fine truffle dining at local restaurants, a marketplace, and public lectures.
l. The fungus grows west of the Cascade Mountains from the southern Puget Sound
region of Washington, south to southwestern Oregon
at elevations from near sea level up to 425 m (1,394.4 ft) in pure stands of Pseudotsuga menziesii forests up to 100-years-old, or Pseudotsuga mixed with Tsuga heterophylla, Picea sitchensis or Alnus species. It is often found in Christmas tree plantations as young as five years. Fruit bodies are produced from September through the middle of March. The fungus is an important component of the diet of Northern flying squirrel
s, and comprises the majority of their diet at certain times of the year.
Tuber
Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to survive the winter or dry months and provide energy and nutrients for regrowth during the next growing season and they are a means of asexual reproduction...
. Described as new to science in 2010, the North American species is found on the western coast of the United States, from northern California
Northern California
Northern California is the northern portion of the U.S. state of California. The San Francisco Bay Area , and Sacramento as well as its metropolitan area are the main population centers...
to southern British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
west of the Cascade Range
Cascade Range
The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...
. A mycorrhiza
Mycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....
l fungus, it grows a symbiotic association with Douglas fir. It overlaps in distribution with the closely related T. gibbosum
Tuber gibbosum
Tuber gibbosum is a species of truffle in the genus Tuber. It is found in the Pacific Northwest region of the United States, where it grows in an ectomycorrhizal association with Douglas-fir.-Taxonomy and phylogeny:...
, but they have different growing seasons: T. oregonense typically appears from October through March, while T. gibbosum grows from January to June. The fruit bodies
Ascocarp
An ascocarp, or ascoma , is the fruiting body of an ascomycete fungus. It consists of very tightly interwoven hyphae and may contain millions of asci, each of which typically contains eight ascospores...
of the fungus are roughly spherical to irregular in shape, and resemble small potatoes up to 5 cm (2 in) in diameter. Inside the truffle is the gleba
Gleba
Gleba is the fleshy spore-bearing inner mass of fungi such as the puffball or stinkhorn.The gleba is a solid mass of spores, generated within an enclosed area within the sporocarp. The continuous maturity of the sporogenous cells leave the spores behind as a powdery mass that can be easily blown away...
, which is initially white before it becomes a marbled tan
Tan (color)
Tan is a pale whiteish, tawny shade of white. The name is derived from tannum used in the tanning of leather.The first recorded use of tan as a shade name in English was in the year 1590....
color. The large, often thick-walled, and strongly ornamented spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
s are produced in large spherical asci
Ascus
An ascus is the sexual spore-bearing cell produced in ascomycete fungi. On average, asci normally contain eight ascospores, produced by a meiotic cell division followed, in most species, by a mitotic cell division. However, asci in some genera or species can number one , two, four, or multiples...
. The truffle is highly prized for its taste and aroma. Attempts to cultivate the truffles in Christmas tree farms
Christmas tree cultivation
Christmas tree cultivation is an agricultural, forestry, and horticultural occupation which involves growing pine, spruce, and fir trees specifically for use as Christmas trees. The first Christmas tree farm was established in 1901, but most consumers continued to obtain their trees from forests...
have been successful.
Taxonomy and phylogeny
The species was first officially describedSpecies description
A species description or type description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species which have been described previously, or are...
and named in a 2010 Mycologia
Mycologia
Mycologia is a peer-reviewed scientific journal that publishes papers on all aspects of the fungi, including lichens. It first appeared as a bimonthly journal in January of 1909, published by the New York Botanical Garden under the editorship of William Murrill. It became the official journal of...
publication, although Tuber oregonense had previously been used as a provisional name (as Tuber oregonense Trappe & Bonito) in a number of field guide
Field guide
A field guide is a book designed to help the reader identify wildlife or other objects of natural occurrence . It is generally designed to be brought into the 'field' or local area where such objects exist to help distinguish between similar objects...
s and other popular publications for several years. The type specimen was collected from Benton County, Oregon
Benton County, Oregon
-National protected areas:*Siuslaw National Forest *William L. Finley National Wildlife Refuge-Demographics:As of the census of 2000, there were 78,153 people, 30,145 households, and 18,237 families residing in the county. The population density was 116 people per square mile . There were 31,980...
on 3 February, 2007 along U.S. Route 20 in Oregon
U.S. Route 20 in Oregon
U.S. Route 20 in Oregon is a major east–west cross-state highway, especially east of the Cascade Mountains. It connects U.S. Route 101 in Newport on the central Oregon Coast to the Idaho state line east of Nyssa.- Route description :...
.
The specific epithet oregonense derives from the name Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
and the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
suffix -ense (relating to), in reference to western Oregon being its central region of abundance. The fungus is commonly
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
known as the Oregon white truffle. Truffle authority James Trappe was initially intending to name the species as a variety of Tuber gibbosum (i.e., as Tuber gibbosum var. oregonense) before molecular analysis revealed that it was clearly genetically distinct enough to warrant being designated a separate species.
T. oregonense is part of the Gibbosum clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
of the genus Tuber
Tuber
Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to survive the winter or dry months and provide energy and nutrients for regrowth during the next growing season and they are a means of asexual reproduction...
. Species in this clade have "peculiar wall thickenings on hyphal tips emerging from the peridial surface at maturity."
Description
The fruit bodies of T. oregonense are hypogeous (growing in the ground), typically 0.5 – broad (although specimens up to 7.5 cm (3 in) have been recorded). Smaller specimens are spherical or nearly so, and have random furrows; larger specimens are more irregular in shape, lobed and deeply furrowed. Young fruit bodies have a white peridiumPeridium
The peridium is the protective layer that encloses a mass of spores in fungi. This outer covering is a distinctive feature of the Gasteromycetes.-Description:...
, as the truffle matures it develops red to reddish-brown or orangish-brown patches; with age it becomes orange-brown to reddish-brown overall and often develops cracks on the surface. The peridium is 0.2–0.4 mm thick, and the surface texture ranges from relatively smooth to covered with tiny "hairs" that are more dense in the furrows, and more scattered on the exposed lobes. The gleba
Gleba
Gleba is the fleshy spore-bearing inner mass of fungi such as the puffball or stinkhorn.The gleba is a solid mass of spores, generated within an enclosed area within the sporocarp. The continuous maturity of the sporogenous cells leave the spores behind as a powdery mass that can be easily blown away...
is solid, in youth the fertile tissue is whitish and marbled with mostly narrow, white, hypha
Hypha
A hypha is a long, branching filamentous structure of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or...
-stuffed veins that emerge throughout the peridium to its surface. In maturity, the fertile tissue is light brown to brown from the color of the spores, but the marbling veins remain white. The odor and flavor of the flesh are mild in youth, but soon become strong, pungent and complex, or "truffly".
The spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
s are ellipsoid to somewhat spindle-shaped with narrowed ends, and light brownish in color. The size of the spores varies depending upon the type of asci in which they develop: in one-spored asci
Ascus
An ascus is the sexual spore-bearing cell produced in ascomycete fungi. On average, asci normally contain eight ascospores, produced by a meiotic cell division followed, in most species, by a mitotic cell division. However, asci in some genera or species can number one , two, four, or multiples...
they measure 42.5–62.5 by 17.5–30 µm; in two-spored asci they are 32.5–50 by 15–25 µm; in three-spored asci they are 27.5–45 by 15–25 µm; in four-spored asci they are 25–38.5 by 13–28 µm; in five-spored asci 28–34 by 22–25 µm (all sizes excluding surface ornamentation). The spore walls are 2–3 µm thick and are covered with a honeycomb-like (alveolate) network. The cavities of the honeycomb typically have five or six sides, and the corners form spines that are 5–7 µm tall by 0.5 µm thick. A "microreticulum" appears in some spores when the light microscope objective
Objective (optics)
In an optical instrument, the objective is the optical element that gathers light from the object being observed and focuses the light rays to produce a real image. Objectives can be single lenses or mirrors, or combinations of several optical elements. They are used in microscopes, telescopes,...
is focused on the optical cross section but not on the spore wall surface, or on scanning electron microscopy micrographs of the surface. Young asci range in shape from spherical to broadly ellipsoid to ovoid (egg-shaped) or pyriform (pear-shaped); sometimes the base of the ascus is narrowed like a stipe
Stipe (mycology)
thumb|150px|right|Diagram of a [[basidiomycete]] stipe with an [[annulus |annulus]] and [[volva |volva]]In mycology a stipe refers to the stem or stalk-like feature supporting the cap of a mushroom. Like all tissues of the mushroom other than the hymenium, the stipe is composed of sterile hyphal...
,and measures up to 15 by 7 µm. Mature asci are spherical to broadly ellipsoid or misshapen from the pressure of crowded spores within. They are hyaline
Hyaline
The term hyaline denotes a substance with a glass-like appearance.-Histopathology:In histopathological medical usage, a hyaline substance appears glassy and pink after being stained with haematoxylin and eosin — usually it is an acellular, proteinaceous material...
(translucent), thin-walled, 60–85 by 65–75 µm, 1–4-(occasionally 5)-spored, and astipitate (without a stipe) at maturity.
The peridiopellis (the cuticle of the peridium) is 200–300 µm thick plus or minus 80 µm of tightly interwoven hypha
Hypha
A hypha is a long, branching filamentous structure of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or...
e that are 3–5 (sometimes up to 10) µm broad. The cells are short and have nearly hyaline walls that measure 0.5–1 µm thick; the interior veins emerge through the peridium the cells and often form a localized tissue of rounded cells up to 12 µm broad. The degree to which the surface is covered with fine "hairs" is variable; these hairs are made of tangled hyphae and emergent thin-walled hyphal tips 2–5 µm in diameter, some even and smooth, some with granulated
Granule (cell biology)
In cell biology, a granule is a small particle. It can be any structure barely visible by light microscopy. The term is most often used to describe a secretory vesicle.-Leukocytes:...
surfaces and some with moniliform walls (resembling a string of beads) that are irregularly thickened by hyaline bands that are 0.5–2 µm wide. The subpellis (the tissue layer immediately under the pellis) is abruptly differentiated from the pellis, 150–220 µm thick, and comprises interwoven, nearly hyaline, thin-walled hyphae 2–10 µm wide with scattered cells up to 15 µm wide. The gleba is made of hyaline, thin-walled, interwoven hyphae that are 2–7 µm broad with scattered cells that are inflated up to 15 µm.
Similar species
Tuber oregonense closely resembles Tuber gibbosum, which grows in the same habitats, but may be distinguished by the structure of its peridium, and differences in spores size and shape. Further, Tuber gibbosum grows from January to June.Edibility
Tuber oregonense is a choice edibleEdible mushroom
Edible mushrooms are the fleshy and edible fruiting bodies of several species of fungi. Mushrooms belong to the macrofungi, because their fruiting structures are large enough to be seen with the naked eye. They can appear either below ground or above ground where they may be picked by hand...
species. Its odor has been described as ""truffly", a complex of garlic, spices, cheese, and "indefinable other essences"; the fungus is prized after by commercial truffle harvesters and consumers for its intense fragrance. Because they grow in the topsoil and needles, they are considered to have a more "floral" and "herbal" flavor profile than related European truffles. Some individuals have had success in growing the truffles in Christmas tree farms in Oregon. The species has been commercially harvested in the Pacific Northwest since the 1980s. The Oregon Truffle Festival has been held in Eugene
Eugene, Oregon
Eugene is the second largest city in the U.S. state of Oregon and the seat of Lane County. It is located at the south end of the Willamette Valley, at the confluence of the McKenzie and Willamette rivers, about east of the Oregon Coast.As of the 2010 U.S...
yearly since 2006 to coincide with the maturing of the truffle in late January; it features activities such as cultivation seminars, truffle hunting excursions, winery tours, fine truffle dining at local restaurants, a marketplace, and public lectures.
Ecology, habitat and distribution
Like all Tuber species, T. oregonense is mycorrhizaMycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....
l. The fungus grows west of the Cascade Mountains from the southern Puget Sound
Puget Sound
Puget Sound is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean — Admiralty Inlet being the major connection and...
region of Washington, south to southwestern Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
at elevations from near sea level up to 425 m (1,394.4 ft) in pure stands of Pseudotsuga menziesii forests up to 100-years-old, or Pseudotsuga mixed with Tsuga heterophylla, Picea sitchensis or Alnus species. It is often found in Christmas tree plantations as young as five years. Fruit bodies are produced from September through the middle of March. The fungus is an important component of the diet of Northern flying squirrel
Northern Flying Squirrel
The Northern flying squirrel is one of two species of the genus Glaucomys, the only flying squirrels found in North America . Unlike most members of their family, flying squirrels are strictly nocturnal...
s, and comprises the majority of their diet at certain times of the year.
External links
- North American Truffling Society Side-by-side comparison of T. oregonense and T. gibbosum