''Phaeolus schweinitzii'', commonly known as velvet-top fungus, dyer's polypore, dyer's mazegill, or pine dye polypore, is a fungal

plant pathogen Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomy ...

that causes

butt rot Butt rot is a disease of plants, mostly trees, caused by fungi. The fungus attacks the moist, poorly protected undersurface of tree trunk's thickest part (the "butt" above the root, as opposed to "top"), where the end of the stem makes contact wit ...

conifer 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 ext ...

s such as

Douglas-fir The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Oregon pine, and Columbian pine. There are three va ...

spruce A spruce is a tree of the genus ''Picea'' (), a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. ''Picea'' is the sole genus in the subfam ...

, fir, hemlock,

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

, and

larch Larches are deciduous conifers in the genus ''Larix'', of the family Pinaceae (subfamily Laricoideae). Growing from tall, they are native to much of the cooler temperate northern hemisphere, on lowlands in the north and high on mountains fur ...

. ''P. schweinitzii'' is a polypore, although unlike

bracket fungi Polypores are a group of fungi that form large fruiting bodies with pores or tubes on the underside (see Delimitation for exceptions). They are a morphological group of basidiomycetes-like gilled mushrooms and hydnoid fungi, and not all polypo ...

the

fruiting body The sporocarp (also known as fruiting body, fruit body or fruitbody) of fungi is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne. The fruitbody is part of the sexual phase of a fungal life cy ...

may appear terrestrial when growing from the roots or base of the host tree. The fruiting bodies, appearing in late summer or fall, commonly incorporate blades of grass, twigs, or fallen pine needles as they grow. They are tannish with darker brown centres, with orange to pale margins on young specimens. They may grow beyond 25 cm in diameter. As the fruiting bodies age, the pore surface turns from yellow to greenish yellow, the top becomes darker, and the yellow-brown

flesh Flesh is any aggregation of soft tissues of an organism. Various multicellular organisms have soft tissues that may be called "flesh". In mammals, including humans, ''flesh'' encompasses muscles, fats and other loose connective tissues, but ...

becomes harder and more wood-like. The pores bruise brown. The

spores 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, ...

are white, elliptical, smooth, and

inamyloid In mycology a tissue or feature is said to be amyloid if it has a positive amyloid reaction when subjected to a crude chemical test using iodine as an ingredient of either Melzer's reagent or Lugol's solution, producing a blue to blue-black stain ...

. The effect, impact and significance of infection by this fungus is rooted in the fact that it causes brown rot, which degrades the cellulose. Thus there is a loss of tensile strength which often leads to brittle fracture near the stem base, even at a fairly early stage of decay. Decay initiated above ground can lead to branch snap or breakout. ''P. schweinitzii'' is native to

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

and

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelag ...

, and has been identified as an exotic species in

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

, and

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring coun ...

. It is not edible. As its common name suggests, the dyer's polypore is an excellent natural source of green, yellow, gold, or brown

dye A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution and ...

, depending on the material dyed and the

mordant A mordant or dye fixative is a substance used to set (i.e. bind) dyes on fabrics by forming a coordination complex with the dye, which then attaches to the fabric (or tissue). It may be used for dyeing fabrics or for intensifying stains in ...

used. ''P. schweinitzii'' is named after

Lewis David de Schweinitz Lewis David de Schweinitz (13 February 1780 – 8 February 1834) was a German-American botanist and mycologist. He is considered by some the "Father of North American Mycology", but also made significant contributions to botany. Education ...

, a

Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...

-born Moravian minister and important early

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...

mycologist Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans, including as a source for tinder, traditional medicine, food, and entheogens, as ...

. Similar species include '' Heterobasidion irregulare'', '' H. occidentale'', ''

Inonotus dryophilus ''Inonotus dryophilus'' is a plant pathogen. References External links Index FungorumUSDA ARS Fungal Database
Fungal plant pathogens and diseases Inonotus, dryophilus Fungi described in 1904 {{fungus-plant-disease-stub ...

'', and '' Onnia tomentosa''.

References

{{Taxonbar, from=Q1314913 Wood-decay fungi Fomitopsidaceae Fungal tree pathogens and diseases Fungi described in 1821 Fungi of Europe Fungi of North America Inedible fungi Natural dyes Taxa named by Elias Magnus Fries