Amanita augusta

Everyone seems to know about the Amanita muscaria, the Fly Agaric, the Magic Mushroom or that "classic" red toadstool. In that same family of mushrooms there is a mushroom called Amanita augusta, and it is one of the most majestic mushrooms I have ever seen.

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I first encountered this mushroom on a foray with my study group during the middle of summer. We had not seen any large fruiting body of mushrooms since the Gyromitra's season ended, so this was particularly exciting for all of us myco-geeks. Henry was the first to discover it and called me over. I typically carry my Canon 80D with a 105mm Macro lens attached for photographing fungi close up. As I moved closer with my camera, Henry moved a bit of fern away to reveal the biggest Amanita augusta I had ever seen. This specimen was in its prime - full mushroom glory. It had a perfect ring of spots (veil remnants) around the cap which was about as wide as it was tall. The deep coffee colored cap was juxtaposed by the yellowish stipe (stem) and all of the scaly textures along its surface. It took my breath away and I just had to sit and admire it for a minute.

Within the genus Amanita, there are 6 sections common to the Pacific Northwest-Section Amanita, Section Validae, Section Lepidella, Section Phalloideae, Section Caesareae, and Section Vaginatae - there are more, but not common in our area. The Amanita augusta falls under the Section Validae and are put into this group because the, "Fruitbodies variably staining reddish or brownish. Partial veil prominent; volva usually weakly developed. Spores amyloid" (Siegel, p. 33). Amanitas are ectomycorrhizal, that means they are in a mutual beneficial relationship with certain plant roots (in this case certain trees), where the fungus gets sugars exuded from the roots and in turn gives the tree access to water and nutrients harvested by the mycelium. Because of this echtomycorrhizal relationship, these Amanitas can only grow with these certain trees. This makes our forests and ecology that much more important!

Henry wandered away as I kneeled to the ground to tuck the straggling fern branches out of the way. This Amanita augusta deserved a photoshoot reserved for the stars. I kneeled on the gravel, elbows digging into the shards of rock and got to work. I took photos that would rival any fungi photographer, but it wasn't hard to do with such a showy specimen. Whenever I photograph a mushroom, especially for an identification review, I keep some of the basics in mind:

  • Even lighting- Don't shoot in bright sun with lots of contrast

  • In it's habitat- take a photo of the specimen in it's habitat, BEFORE you harvest it

  • Take photos of the cap, from the top and from the side

  • Focus on the margins- sometimes a defining characteristic is the margin of a cap

  • Dig it up- don't just pick a mushroom, dig it up, so you can see all of the fruiting body

  • Flip the mushroom upside-down to photograph those gills (or hymenium surface)!

  • Make sure to take clear photos

  • Staining - if you handled a mushroom and it's staining, take a photo of that reaction

Amanita augusta
Classification:
Fungi
Dikarya
Basidiomycota
Agaricomycotina
Agaricomycetes
Agaricomycetidae
Agaricales
Amanitaceae
Amanita

Description:
Cap: 5-15 cm diameter, dark brown to lemon yellow with a darker center and lighter margin, surface is greasy or a bit viscid and covered in universal veil patches, cap is round when young, then becoming flat or convex when mature.
Gills: attached, blade-like, cream to yellow colored, closely spaced and crowded
Stipe: is about 8-15 cm tall, a swollen or enlarged base, lower surface covered in scales and staining reddish, and the rest of the stipe a powdery white
Partial Veil: looks like a yellow skirt around the neck of the stipe
Volva: Look for sheets of universal veil remnants around the base of the stipe in rings, usually in the soil.
Flesh: whitish
Spore print: white
Spores: 8.5x6 um, broadly elliptical and smooth, amyloid, basidia not clamped at base
No odor

Found in small groups or solitary in early fall under Sitka Spruce.

On October 1st, I headed back into the woods to see if I could find another Amanita augusta specimen, so I could get a spore print. Just as we were about to leave, there was a prime brownish-yellow amanita sitting by the side of the path. Diana spotted it first and called me over. Because it was so young I was unsure if it was the A. augusta I was looking for. I took it home and made a spore print and then looked at the spores under the microscope. I mounted the spores in Melzer's reagent to see if I would get a reaction. Sure enough, they are amyloid! With that information I was able to start keying out the mushroom.

I started in Mushrooms Demystified, by David Arora, and keyed it out to Amanita aspera. To check and see if that was the right identification, I then looked in Amanitas of North America by Britt Bunyard & Jay Justice, but this Amanita wasn't listed. This is not unusual, it just means that the scientific names might have been changed. So I hopped on to Mycobank to check to see if the name was current. Then things started to get confusing. The name is current, but there were so many synonyms for this, including other genera. I decided to check out what my other books had to say before moving to an online search. I looked up A. aspera in Mushrooms of the Redwood Coast by Noah Siegel and Christian Schwarz, and in Mushrooms of the Pacific Northwest by Steve Trudell & Joe Ammirati, and discover the name A. aspera was just a synonym to the mushroom A. augusta. There are other synonyms to Amanita augusta as well: A. franchetii (Boud.) and A. aspera.

I still need to do some more research to give a definitive answer as to what this mushroom is, but you can see its stature, and spores in the following photos.

While researching Amanita's for this post, I came across a mold that parasitizes Amanitas in the back of Amanitas of North America. On a couple trips to the woods I found a very melty, goopy mushroom remnant that fascinated me. I took some photos of it, not realizing what it was. As I looked through my books I found this mention of Syzygites megalocarpus, or a Mushroom Pin Mold. I am looking into that mold as a possibility to what this was. Fungi and molds that parasitize other mushrooms is a fascinating subject, and I am always on the lookout for examples of this connection. ​

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Resources:

https://www.mycobank.org/page/Simple%20names%20search
Arora, David (1986). Mushrooms Demystified, 2nd ed.
Bunyard, Britt A. & Jay Justice (2020). Amanitas of North America
​Largent, David. How to Identify Mushrooms to Genus I: Macroscopic Features
Largent, David & David Johnson. How to Identify Mushrooms to Genus III: Microscopic Features
Siegel, Noah and Christian Schwarz (2016). Mushrooms of the Redwood Coast: A Comprehensive Guide to Fungi of Coastal Northern California
Trudell, Steve & Joe Ammirati (2009). Mushrooms of the Pacific Northwest


My iNaturalist observations:
https://www.inaturalist.org/observations/55013707
https://www.inaturalist.org/observations/61507564
​https://www.inaturalist.org/observations/61507395