Witness the Unbelievable Transformation of Fungi Xylania Polymorpha

This week’smushroomis Xylaria polymorpha, commonly known as Dead Man’s Fingers. It was found on 5/6/2021 growing out of a dead stump just south of the castle. There are a few different species of Xylaria that grow in the area, and they’re only distinguishable using a microscope, but we’re going to assume this is X. polymorpha (the other species it would likely be is X. longipes).

X. polymorpha is commonly found in woodlands across North America east of the Rockies. As expected of amushroomgrowing out of a dead stump, X. polymorpha is saprobic and consumes the dead wood for nutrition. What is unique about X. polymorpha is that it releases spores over a period of months, whereas mostmushroomsrelease their spores over a period of days/weeks. In spring, the juvenile fruiting bodies (conidiophores) produce asexual spores that look like white dust and coat the tips of the fruiting bodies (as seen in the pictures). In late summer/fall, sac like structures calledperitheciaedevelop just beneath the surface layer of the fruiting body and produce sexual spores. This is another fungus that is capable of both asexual and sexual reproduction. The fungus has also been found to possess compounds known to cause cell damage/cell death and scientists have tried (without success) to use these compounds to fight HIV.

The reason for the late release of this email today is because I found what I think is a Northern Softshell Spiny Turtle (Apalone spinifera spinifera) and I wanted to make sure I attached some pictures in the email. It’s conservation status in New York State is “imperiled” per iNaturalist. However, Manhattan is too far east of its native range of western New York state, so I imagine this turtle was probably released into the lake. Nonetheless, it’s fun to think about how it got here (naturally or with a helping hand) and if there are other softshell turtles lurking in the murky lake water.X. polymorpha is commonly referred to as “Dead man’s fingers” because of the appearance of its fruiting body. The “mushrooms of X. polymorpha are cylindrical and covered with a bumpy, carbon-like coating that gives it a dark brown or gray coloration (2, 3). Fully matured fruiting bodies can grow up to 10 cm tall and often grow out of the soil near decaying trees in “finger-like” clusters of three (3). Its very distinctive morphology makes it relatively easy to identify.

Genetic Transformation And Vector Developments In Filamentous Fungi

X. polymorpha is primarily a saprobe of wood and is widely distributed throughout deciduous forests in North America and Europe (2). Its ability to decompose wood makes it an important organism for recycling fixed carbon.

Like most ascomycetes, X. polymorpha gains its energy through absorptive nutrition--the process of secreting digestive enzymes that break down complex carbohydrates, allowing the fungus to absorb smaller products for nutrients to fuel growth and reproduction (2).

Sexual fruiting bodies of X. polymorpha tends to develop mid-to-late year, any time from May to November (2). Its sexual spores are found in dark perithecia that are embedded in a white stroma on the interior of the ascocarp (3). The fruiting body is tough and durable, allowing it to persist for months or longer to slowly release spores--a feature uncommon to many fungi (2). The slow release of spores is thought to allow this species to have a large distribution range within its habitat (2).

Genetic Transformation Systems In Fungi, Volume 2 On Apple Books

The asexual structure of X. polymorpha is not long-live and therefore, does not have many of the phenotypes of the sexual structures. The formation of asexual spores leads to a white/gray-ish appearance with a powdery texture from conidia (3).

Its fruiting structures are known to produce diverse classes of bioactive secondary metabolites, including several antifungal metabolites. Some examples are multiploides A and B, polypropionates, and xylarinic acid A and B (4).

X. polymorpha contains a 43.52 MB genome, 48.5% GC content, 951 contigs, 74, 443 contig N50, 174 contig L50, 947 scaffolds, 74, 858 scaffold N50, and 173 scaffold L50 (5, 6).

The Results Are In!

While X. polymorpha is primarily a saprobe wood in deciduous forests, if a tree is injured or under stress, it may act as a weak pathogen by entering through a wound. It causes “soft rot” by breaking down the polysaccharides within wood, only leaving behind unconnected lignin and cellulose (1, 2).

[2] Vogini, J. & Powell, S. (2001). The Virtual Nature Trail at Penn State New Kensington, Species Pages. The Pennsylvania State University. https://www.dept.psu.edu/nkbiology/naturetrail/speciespages/deadmansfingers.htm

[4] Jang, Y. W., Lee, I. K., Kim, Y. S., Seok, S. J., Yu, S. H., & Yun, B. S. (2009). Chemical Constituents of the Fruiting Body of Xylaria polymorpha. Mycobiology, 37(3), 207–210. https://doi.org/10.4489/MYCO.2009.37.3.207. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3749389/Xylaria polymorpha appears throughout the year at the base of beechwood stumps and occasionally on other buried hardwoods. Dead Man's Fingers is a very apt common name for this dull-looking species, which usually arises in tufts of three to six fingers that are often bent and give the impression of arthritic black knuckles.

Genetic Transformation Of Filamentous Fungi: Achievements And Challenges

Often appearing in palmate bunches, the stromata comprise white infertile finger-like forms with a black coating containing the flasks within which the asci (singular ascus) produce their spores. Known as 'flask fungi', these black compound fruitbodies are difficult to spot in dark woodlands.

A close-up picture of the surface of an adult fruitbody is shown above, and its granular form is clearly evident; however, the specific epithet

Concealed beneath those surface bumps are roundish chambers lined with spore-producing structures known as asci - hence these fungi belong to the phylum Ascomycota, the largest (by species numbers) section of the fungal kingdom.

Xylaria Polymorpha, Dead Man's Fingers Fungus

The brownish Dead Man's Fingers shown on the left are in between the asexual and sexual reproductive phases of this ascomycetous fungus.

Shown above and immediately below are at the conidial (asexual) spore-producing stage, when the 'fingers' often turn pale blue. The pictures were taken in Wisconsin and in Illinois.

Many of the fungi whose lifecycles include both asexual (via conidiospores) and sexual (via either ascospores or basidiospores caused great confusion in the early days of fungal taxonomy. Several of them were given separate binomial scientific names for each of these stages, because they were thought to be quite different species. If you compare the light blue 'Dead Man's Fingers' with those in the picture at the top of this page, I think you will readily accept that this was hardly a stupid mistake but quite understandable.

Individual fingers vary from 1 to 3cm in diameter and are usually between 3 and 8cm long when fully developed. The surface is initially white or greyish and covered in a fine pallid powder (conidia) during the asexual stage, later becoming slightly granulated and darkening through brown to black, sometimes with greenish or bluish tinges.

As seen on the left, inside the communal fruitbody known as a stroma (plural stromata) the flesh is white; it is quite hard. Near the surface are spore-producing cavities known as perithecia - visible in this picture as black dots against the white background. There is a tiny pore-like hole in the top of each perithecium, and when the asci explode and eject their spores this is their exit route to the great world outside.

Produced within structures known as asci (singular ascus), the ascospores are dark brown (when fully developed), smooth, fusiform (spindle-shaped) or banana shaped, and 20-30 x 5-9μm. (Ascomycete fungi generally have spores much larger than those of most basidiomycete species.)

Unusually, the spores shown here contain several guttules (oil-like drops) up to about 5μm in diameter, whereas most authorities refer to the spores of

Species this fungus is also capable of asexual reproduction via conidiospores (often referred to as conidia), which are smaller than the ascospores, smooth, ellipsoidal and hyaline. The pale blue-grey powdery conidiospores are still visible on the tips of young fruitbodies pictured on the left; they will have been blown or washed away by the time that the ascospores are ripe, and then the surface of the 'fingers' will have become a much darker shade of brown.

Saprobic, and so found on or near (and connected) to the stumps of dead beech trees and, less frequently, other broadleaf tree stumps.

Dead Man's Fingers are indeed wood-rotting fungi, but they specialise in consuming neither the softish cellulose nor the much tougher lignin but rather the polysaccharides - glucan and other minority content compounds of timber that bind the cellulose and lignin together to form what we recognise as wood. As a result, when these and various other ascomycetous fungi have consumed what they can of a dead stump the remainder is a nutrient-rich soft mess that insects and other small creatures are able to feed upon (if other cellulose- or lignin-rotting fungi haven't found it first).

Mainly seen in summer and autumn, but some fruitbodies can usually be found throughout the year. Producing ascospores in autumn and early winter.

Xylaria longipes is similar but slimmer, smaller and less robust. Its fruitbodies are more obviously stalked clubs and they occur most often on the stumps and fallen branches of sycamore trees as well as beeches.

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi

Fascinated by Fungi.

Share :