Hydnellum geogenium

The fungus was described as new to science in 1852 by Elias Magnus Fries. Howard James Banker transferred it to the genus Hydnellum in 1913.

Hydnellum geogenium produces solitary or often confluent basidiocarps with caps (pilei) up to 10 cm wide. The cap surface may be divided into irregular lobes of varying lengths, bearing small wart-like bumps (tuberculate) or radial furrows. Its colour ranges from lemon-yellow to sulphur-yellow or pale yellow, and in damp conditions the surface frequently exudes droplets of reddish fluid. Underneath, the hymenophore (the fertile, spore-bearing surface) consists of downward-pointing spines up to 3 mm long, characteristic of hydnoid fungi. The flesh (context) is initially yellow, darkening to brown with age, and the fruit bodies emit a mild aromatic odour and retain a gentle taste.

The stipe is cylindrical to tapering, reaching up to 3 cm in height and 2 cm in width, and shares the cap's citric yellow hue. Microscopically, the fungal tissue comprises hyphae 2–6 micrometres (μm) wide that bear clamp connections, ensuring proper nuclear distribution during cell division. The ascospores are roughly spherical (subglobose), measuring 4–5 × 3–3.5 μm, and feature a tuberculate surface that may aid in spore dispersal.

Hydnellum geogenium is widely distributed in temperate regions of northern hemisphere, with its northern range extending to the Polar circle. It forms mycorrhizae with Picea trees. In Europe, the northern extent of its range is southeast Norway. It appears on the red lists of Germany, Poland, and Sweden. H. geogenium is considered endangered in Switzerland.

{{Reflist|colwidth=30em|refs=

{{cite journal |last=Banker |first=H.J. |title=Type studies in the Hydnaceae – V. The genus Hydnellum |journal=Mycologia |year=1913 |volume=5 |issue=4 |pages=194–205 |url=http://www.cybertruffle.org.uk/cyberliber/59350/0005/004/0194.htm |doi=10.2307/3753385 |jstor=3753385 }}

{{cite journal |last1=Gulden |first1=G. |last2=Hanssen |first2=E.W. |year=1992 |title=Distribution and ecology of stipitate hydnaceous fungi in Norway, with special reference to the question of decline |journal=Sommerfeltia |volume=13 |pages=30, 38 |doi=10.2478/som-1992-0001 |url=http://www.nhm.uio.no/forskning-samlinger/forskning/publikasjoner/sommerfeltia/sm_abstr.htm |doi-access=free}}

{{cite journal |last1=Steglich |first1=W. |last2=Jendrny |first2=B. |title=Geogenin, ein neuartiger Pyronfarbstoff aus Hydnellum geogenium |trans-title=Geogenin, a new kind of pyrone pigment from Hydnellum geogenium |journal=Beihefte zur Sydowia Annales Mycologici |series=Series II |year=1979 |pages=378–380 |language=de}}

{{cite journal |last=Karsten |first=Petter A. |title=Enumeratio Hydnearum Fr. Fennicarum, systemate novo dispositarum |journal=Revue Mycologique Toulouse |year=1881 |volume=3 |issue=9 |pages=19–21 |url=https://www.biodiversitylibrary.org/page/11599314 |language=la}}

{{cite book |last=Ryvarden |first=Leif |year=2024 |title=Hydnoid Genera – A World Synopsis |series=Synopsis Fungorum |volume=50 |publisher=Fungiflora |location=Oslo |url=https://www.fungiflora.no/synopsis-50-hydnoid-genera |page=31}}{{OA}}

{{cite journal |last=Sauter |first=A.E. |title=Diagnosen neuer Pilze |journal=Hedwigia |year=1869 |volume=8 |pages=40–41 |language=de |url=https://www.biodiversitylibrary.org/page/483564}}

{{cite report |last1=Senn-Irlet |first1=B. |last2=Bieri |first2=G. |last3=Egli |first3=S. |title=Lista Rossa Macromiceti. Lista Rossa delle specie minacciate in Svizzera. UV-0718-I |year=2007 |location=Bern |publisher=Ufficio federale dell’ambiente |language=it |url=http://www.bafu.admin.ch/publikationen/publikation/00055/index.html?lang=fr&lang=it}}

{{cite web |title=GSD Species Synonymy: Hydnellum geogenium (Fr.) Banker |url=http://www.speciesfungorum.org/GSD/GSDspecies.asp?RecordID=469494 |publisher=Species Fungorum. CAB International |access-date=2015-01-21}}

{{cite web |last=Phillips |first=R. |title=Hydnellum geogenium |publisher=RogersMushrooms |url=http://www.rogersmushrooms.com/gallery/DisplayBlock~bid~6117~gid~~source~gallerydefault.asp |access-date=2015-01-21 |url-status=dead |archive-url=https://web.archive.org/web/20150122080910/http://www.rogersmushrooms.com/gallery/DisplayBlock~bid~6117~gid~~source~gallerydefault.asp |archive-date=2015-01-22 }}

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geogenium

Category:Fungi described in 1852

Category:Fungi of Europe

Category:Fungi of North America

Category:Inedible fungi

Category:Taxa named by Elias Magnus Fries

Category:Fungus species