Mushroom Monday

Ornate-stalked bolete (Retiboletus ornatipes)

Good evening, friends,

Wow. After a patient wait this summer we finally received all that the rain promises and more. There has been a fungal explosion on and around the preserve (thanks to all the rain from the previous week), and boletes have been abundant in the woods. This week we’re looking at the Ornate-stalked Bolete (Retiboletus ornatipes) which we found under a hickory on Saturday’s walk in Stamford, CT. Not only is the mushroom downright handsome, but even when not producing captivating fruiting bodies this fungus still serves an important ecological function.

The vibrant yellow of the stipe contrasts with the velvet, grey cap

While not much is known about the genus Retiboletus, there was a study published out of China this spring that looked at the species Retiboletus sinensis. The researchers inoculated young oak and pine trees with four different species of ectomycorrhizal fungi (ECMF), including R. sinensis, and found between a 40 to 55% infection rate across the seedlings. About half the trees formed a relationship with the fungus.

The researchers found that the trees with ectomycorrhizal relationships grew larger and displayed higher rates of photosynthesis. The scientists postulated that inoculation of young trees with ECMF could be an effective way to not only boost tree health but also cultivate edible mushrooms.

This photo is from a Retiboletus ornatipes I found last year in Fahnestock State Park.

Reticulation is the distinct webbing that criss-crosses down the stipe. The shape and color of reticulation is an important factor in the ever-difficult challenge of bolete identification. Some boletes have reticulation that is a different color than the stipe, like Porcini, but here we have yellow reticulation on a yellow stipe.

I also watched this video from Anna McHugh (who I’ve definitely run into at some mushroom event which led to a half hour of unsuccessfully trying to figure out where, maybe mycofest?) and she says the mushrooms stain your fingers yellow when you handle them. She also notes that this is an edible mushroom but not “choice”, and that she doesn’t eat them.

The yellow pore surface doesn’t bruise when touched. The grey cap sometimes seems to turn yellow with age.

The etymology breaks down to the Latin prefix Reti- which means “network”, and -boletus which used to be the taxonomic genus that housed all boletes. The species epithet ornatipes means “ornate foot” and refers to the decorated stipe. The suffix -pes means “foot” and is also seen in the species Flammulina velutipes where “velutipes” means “velvet foot”.

Notice the yellow coloring on the margin of the cap

Ecology

As previously noted, the fungus is ectomycorrhizal with hardwood trees. While the mushrooms in the Retiboletus genus can be found across the globe, R. ornatipes appears to be endemic to eastern North America. The mushrooms grow in the summer (particularly in July and August) and are found growing alone or in groups. Both times I’ve found this species I found one solitary shroom. It’s also noted that there is likely a southern species and a northern species that are genetically distinct.

Figure 2 from Reference 2, (Tan, et al 2024)

This was too cool not to post, but this is an image from Reference 2 and the study cited earlier. Check out the difference in root structure of this young pine.

ADK Mushroom Mania

This weekend I’m heading up to the Adirondacks to lead a couple walks at the Adirondack Museum for their Mushroom Mania. We’re going to stay up there and camp for a couple nights too, so next week’s publication will probably be highlights of ADK mushrooms. Can’t wait.

Full moon today. It’s a Blue Supermoon so it will appear full through Wednesday. Gonna go see if I can’t get a glimpse now,

Aubrey

References:

1. Kuo, M. (2017, January). Retiboletus ornatipes. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/retiboletus_ornatipes.html

2. Tan Q, You L, Hao C, Wang J, Liu Y. Effects of four bolete species on ectomycorrhizae formation and development in Pinus thunbergii and Quercus acutissima. BMC Ecol Evol. 2024 Apr 25;24(1):54. doi: 10.1186/s12862-024-02239-w. PMID: 38664655; PMCID: PMC11044466.

3. https://www.inaturalist.org/taxa/348815-Retiboletus-ornatipes