Assessment Notes

Justification

Picipes rhizophilus is a peculiar small polypore with greyish cap and a black stipe base. It inhabits the rhizomes of various steppe grasses, e.g. feather grass (Stipa). It is everywhere a very rare species growing on steppe grasses with special habitat needs and thus in disappearing habitats. It has been much searched for in some countries but records remain rare. The species is in the Red Lists of Austria, Bulgaria, Czechia, France, Germany, Poland, Russian Federation (regional red lists), Slovakia and Switzerland. It is threatened by habitat loss and habitat change. The number of mature individuals has been estimated at 2500-5000, and the subpopulations are very small (<10 mature individuals). There is continuing decline in the number of mature individuals. The species therefore qualifies as VU C2a(i).

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Taxonomic notes

Polyporus cryptopus is currently considered to be a synonym of Picipes rhizophilus.

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Geographic range

Picipes rhizophilus grows in the dry steppe zone in continental Eurosiberia (Russia, Ukraine, Kazakhstan), in the Mediterranean region (Algeria, Morocco, Tunisia), and in coastal dune areas, mostly in agreement with the host grasses. The type site is located in a plateau in Algeria. The area extends from North Africa on Central Europe in the Ukraine, to the Baltic Sea (Mecklenburg-Western Pomerania) to southwestern Siberia (Kazakhstan) and probably even further to the east in little explored steppes of Central Asia (Mongolia, China). It is also present in North America. There is one record from Brazil, one from Argentina, and one from China.

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Population and Trends

Based on GBIF (2019), databases available (see references) and personal communication (Olga Morozova, Sergei Bolshakov) 125 localities are known worldwide but when including unknown localities the total number may be two to four times this: 250-500. The number of mature individuals per locality is estimated as 10 following recommendations in Dahlberg and Mueller (2011). This gives a total population estimate of 2500-5000. The population is declining but the rate is not known.

Population Trend: Decreasing

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Habitat and Ecology

This rare polypore inhabits the rhizomes of various steppe grasses. In Austria it grows exclusively on feather grass (Stipa), further hosts elsewhere in its range are Andropogon, Agropyron (common couch grass), Bothriochloa (bearded grass), Bromus riparius, Calamagrostis (horse grass), Chrysopogon (gold beard), Cynodon (dog tooth grass), Digitaria, Elymus, Elytrigia (hair muck), Festuca (fescue) Koeleria, Lasiagrostis, and Poa. Its trophic guild is unclear, one assumes parasitism (perthobiotic nutrition mode) or a kind of mycorrhiza, but it could also live purely as a saprobiont. The fruiting bodies grow in conjunction with dead leaf sheaths of the grasses. However, loose hyphal nets surround the living grass roots. It always inhabits distinctly dry and mostly sandy soils.

Its main habitat types are natural and semi-natural xerothermic grasslands, like steppes and steppe-like grasslands, seldom grassy open woodlands (Quercus ilex forests), arboreta and parks. It is known from the following vegetation types: Mesobromion, Festuco valesiacae-Stipetum capillatae, Festuco-Brometea, Sisymbrio-Stipetum capillatae, Festucetalia valesiacae, Festucetum vaginatae, seldom Junipero-Populetum albae. Natura 2000 habitat codes are 2340, 6210, 6260, and 62C0.

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Threats

It is threatened by habitat loss, habitat change, abandonment of traditional forms of cultivation (ceasing of mowing or grazing, conversion into agricultural fields, transformation into forests for biomass plant production), bush encroachment, eutrophication through nearby intensive agriculture (airborne nitrogen deposition and from adjacent agricultural areas).

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Conservation Actions

Habitat protection and management, such as controlled grazing and control of bush encroachment, and reduction of nutrient input from adjacent agriculture are needed. Research is needed on distribution area, population size and trends. In some countries it has been assessed as threatened on national Red Lists (Austria - CR, Poland - EN/CR). It is legally protected in Poland.

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Use and Trade

This species is not used or traded.

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Source and Citation

Krisai-Greilhuber, I. 2019. Picipes rhizophilus. The IUCN Red List of Threatened Species 2019: e.T147440473A148038829. Accessed on 22 November 2025.

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• Country occurrence