Hapalopilus rutilans

June 20, 2022

Good evening, friends,

This week’s mushroom is Hapalopilus rutilans, sometimes referred to as Hapalopilus nidulans due to taxonomical disputes we won’t address, and commonly known as the tender nesting polypore or the cinnamon bracket. This mushroom was found on 6/13/2022 up in Manitou. 

Fun Facts

H. rutilans is used as a dye for wool and other fabrics as it endows a subtle purple to your preferred textile. It’s typically not found on the west coast, so there’s even a trading group where folks can barter for and exchange fungi, lichen, and other natural dyes.

The mushroom possesses a neurotoxin known as polyporic acid that is toxic when consumed. This neurotoxin is found in other polypores at significantly lower amounts, however it is particularly prominent in this mushroom. A father and daughter consumed this mushroom, mistaking it for the beefsteak polypore (Fistulina hepatica), and experienced symptoms ranging from visual impairment to severe gastrointestinal distress (reference 4).These two did recover but others have died from the consumption of this mushroom. As it’s known to do with wool, it also turns purple the urine of afflicted individuals.

Continuing with colors, H. rutilans also turns a bright purple in KOH (potassium hydroxide – a chemical used for field identification of fungi). Unfortunately, I didn’t have any KOH on hand but I’ll procure some to carry around at work. A microscope just came in the mail so the Mushroom Monday lab is beginning to get our feet underneath us.

Ecology

H. rutilans is saprobic, growing on dead wood. It is found on five continents – South America and Antarctica withstanding – but is typically only found east of the Rockies in North America. One peculiar note is that it grows on hardwoods in most of the world, but in the seldom instances where it grows west of the Rockies it has been found on conifers – perhaps signaling a different species altogether. It grows spring through fall and is often found on tree limbs that come down in heavy storms.

The mushroom is kidney-shaped and quite spongy to the touch. Hapalopilus means “with a soft cap” – referring to this spongy texture – while rutilans means “reddish”. The mushroom has white spores and, in the photo below, you can see it has cream colored pores (that will turn brown with age). Also notice the brown bruising, typical in young specimens, made by my fingernail on the right. 

Below is a bonus photo I took today of brittlegills (Russula) in the foreground with a sea of ghost pipes (Monotropa Uniflora) – their notorious plant partner – in the background. I wrote about their relationship in a former Mushroom Monday here.

Experience and enjoy the summer solstice tomorrow,
Aubrey

References:
1) Kuo, M. (2018, December). Hapalopilus nidulans. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/hapalopilus_nidulans.html
2)https://www.messiah.edu/Oakes////fungi_on_wood/poroid%20fungi/species%20pages/Hapalopilus%20rutilans.htm
3) https://www.inaturalist.org/taxa/130909-Hapalopilus-rutilans
4) https://pubmed.ncbi.nlm.nih.gov/23937526/
5) https://www.fungusfactfriday.com/170-hapalopilus-nidulans/