''Rhizopogon occidentalis'' is an ectomycorrhizal

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

in the family

Rhizopogonaceae ''Rhizopogonaceae'' are a family of fungi in the order Boletales. The family, first named and described by botanists Ernst Albert Gäumann and Carroll William Dodge in 1928, contains 2 genera and 151 species. The genus ''Fevansia'', formerly thou ...

of the

Basidiomycota Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basi ...

. It occurs most commonly in western North America in association with two-needle and three-needle

pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accep ...

hosts. They are

false truffle A false truffle or a hymenogastrale is any species of fungus that has underground fruiting bodies that produce basidiocarps resembling the true truffles of genus ''Tuber Tubers are a type of enlarged structure used as storage organs for nutri ...

s with fruiting bodies that are yellow on the surface and pale yellow inside. Their edibility is disputed.

Taxonomy

''Rhizopogon occidentalis'' was first described by Sanford Myron Zeller and Carroll William Dodge in 1918 from collections made in Moscow, Idaho; Klickitat Co. and Bingen, Washington; Between Hood River and Mosier, Oregon; and Pacific Grove, California. The Latin name occidentalis means western, likely in reference to the species’ western North American distribution. It is one of the species commonly known as a

due to the shape and location of its fruiting body.

Habitat and distribution

They are distributed primarily across western North America. They colonize trees in sandy soils namely in coastal

dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, f ...

s and

montane forests Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial f ...

as well as interior pine forests.

Morphology

Their fruiting bodies (

basidiocarp In fungi, a basidiocarp, basidiome, or basidioma () is the sporocarp of a basidiomycete, the multicellular structure on which the spore-producing hymenium is borne. Basidiocarps are characteristic of the hymenomycetes; rusts and smuts do not ...

s) are truffle like and 1–4 cm in diameter when dried with a yellow 60-240 um thick peridium and pale yellow gleba. These structures stain reddish with injury Their basidia are clavate and contain 6 or 8 spores. The spores are smooth, ellipsoidal and 7-9 by 3-5 um. They have white hyphae 2–5 mm in width and 5-25 um in length with simple dichotomous branching and thick rhizomorphs. They lack clamp connections and deposits of what is thought to be calcium oxalate found on the mantles of some other members of their genus.

Ecology

They are

ectomycorrhiza An ectomycorrhiza (from Greek ἐκτός ', "outside", μύκης ', "fungus", and ῥίζα ', "root"; pl. ectomycorrhizas or ectomycorrhizae, abbreviated EcM) is a form of symbiotic relationship that occurs between a fungal symbiont, or mycobi ...

l mutualists primarily with two and three needle pines though they are also capable of forming ectomycorrhizal relationships with

Sitka spruce ''Picea sitchensis'', the Sitka spruce, is a large, coniferous, evergreen tree growing to almost tall, with a trunk diameter at breast height that can exceed 5 m (16 ft). It is by far the largest species of spruce and the fifth-larg ...

. Studies and observations of their interactions with bishop pine suggest they are most competitive in newly forested or areas with recent disturbance (such as fire) due their strong

priority effect In ecology, a priority effect is an impact that a particular species can have on community development due to prior arrival at a site. There are two basic types: An ''inhibitory priority effect'' which occurs when a species that arrives first at ...

, and are often outcompeted as forests mature. Early establishment after fire may also be aided by its spores greater heat resistance relative to some cooccurring ectomycorrhizal species. Their fruiting bodies grow underground and are eaten by small mammals, which disperse their spores. Once dispersed, spores can remain dormant for more than four years.

Uses

Edibility

The edibility of this species is disputed. One source describes it as inedible while others describe it as having a mild odor and taste

Lumber industry

Traits like its speed of colonization and its low likelihood of long term establishment make the species potentially commercially useful in the lumber industry.

References

External links

* {{Taxonbar, from=Q10653122 Fungi of North America Rhizopogonaceae Fungi described in 1918 Fungus species Taxa named by Sanford Myron Zeller