Amanita parcivolvata, commonly known as the Ringless False Fly Agaric or False Caesar’s Mushroom, is a fungus that is indigenous to the eastern and southeastern regions of North America. This particular species is easily recognized by its unique features, including a vibrant red to orange cap adorned with scattered warts, pale yellow gills, and a dusty yellow stem that lacks a ring, hence its “ringless” characteristic, and has remaining fragments of the universal veil at its base.[i]
Amanita parcivolvata was initially identified and documented by Charles Horton Peck in 1900 under the name Amanitopsis parcivolvata, and was reclassified in 1910 by the American mycologist William Alphonso Murrill into the genus Vaginata, which is no longer in use today. However, It wasn’t until 1941 that J.E. Gilbert introduced the current name for this species through another reclassification, placing it back into the genus Amanita.
The etymology of the name “Amanita parcivolvata” has its roots in the Greco-Latin language. The genus name “Amanita” originates from the Greek word “amānēs,” which signifies “unadulterated.” This term aptly describes the association of the genus with mushrooms that possess a distinct cap and stem structure. On the other hand, the epithet “parcivolvata” is a fusion of two Latin words. “Parci” translates to “without” or “lacking,” while “volvata” denotes something “rolled-up” or “wrapped.” Consequently, the name “Amanita parcivolvata” highlights the species’ identifiable features, particularly the absence or reduction of a prominent ring or volva.
Cap: The cap of Amanita parcivolvata measures 1.5-12.5 cm in diameter. Initially round, it becomes convex and eventually flattens or develops a slight depression. The central portion of the cap is reddish in color, transitioning to shades of orange or yellow-orange near the margin. The surface of the cap is smooth but can become tacky when wet. The surface may also exhibit remnants of the universal veil as scattered, loose yellow warts. The margin of the cap is radially lined. With age, the appearance of the cap may become sordid or dingy.
Flesh: The flesh of this species is pale yellow. It does not change color when bruised or damaged.
Gills: The gills of this species are completely or nearly free from the stem. They are close or crowded. In mass, the gills are pale yellow with a dusted appearance, but individual gills may be white. There may also be infrequent to occasional interspersed short, truncated gills.
Stem: The stem of A. parcivolvata measures 2-12 centimeters in length and up to about 1.5 centimeters in thickness. The stem is often apically tapering with a basal bulbous swelling. It characteristically lacks a ring. Its surface is yellow and powdery in texture. Lastly, fragile remnants of the universal veil are usually scattered around on the lower part of the stalk. These particles are easily removed and are frequently left behind on the ground when the mushroom is picked.
Spores: Spores of Amanita parcivolvata measure 8-10 x 6-8 µm in size. They are smooth in texture, have an ellipsoid shape, and are inamyloid, meaning they do not exhibit staining characteristics.
Spore Print: The spore of this species is white.
Smell: This species does not have a distinctive odor.
Flavor and Edibility: This species is considered poisonous, as such it is inedible.
Habitat: Amanita parcivolvata can be found growing solitary or clustered on the ground in deciduous woods and disturbed areas, such as lawns or woodland roads. Furthermore, it is known for its mycorrhizal associations primarily with oaks and occasionally with pines.
Range: This species is indigenous to the eastern and southeastern United States. It is known to occur all along the Atlantic coastline from Florida to as far north as New Jersey and as far west as Ohio.
Fruiting Season: A. parcivolvata fruits from spring to late summer and early fall.
Several species can be confused with Amanita parcivolvata due to their similar appearance. Some of these species include:
- Amanita Caesarea: Confusing A. parcivolvata with the edible A. caesarea poses the greatest risk. Fortunately differentiating these two species is relatively easy. The presence of a well-developed ring and persistent sack-like volva on the edible Amanita caesarea and the absence of these features on Amanita parcivolvata are sufficient to distinguish these two species from each other for even the most inexperienced and inaction mushroom picker.
- Amanita muscaria (Fly agaric): A. muscaria can be differentiated from A. parcivolvata by its overall stockier appearance, more prominent warts on the cap surface, a persistent ring, and a characteristic stem base encircled by concentric zones of shagginess.
- Amanita flavoconia (Yellow wart): This species is smaller in size and has a distinct orange-yellow color with dark yellow volva patches. This species also has a ring.
Amanita parcivolvata can be easily confused with several other species of Amanitas, leading to potential misidentification. Several mycological field guides have documented common errors in distinguishing these species. Given the challenges in accurate identification and the potential risks associated with consuming Amanitas, it is advisable to consider all Amanitas as poisonous and avoid consuming them altogether.
Toxicity and Safety
Amanita parcivolvata, like many other Amanita species, is considered poisonous. Its toxicity can be attributed to the presence of Amatoxins (amaninamide and alpha-amanitin) and other harmful substances such as phallotoxins (phalloidin and phallacidin) and virotoxins (toxovirin). These toxins exert detrimental effects on various cellular processes in the human body such as cellular homeostasis and replication.
Amatoxins, phallotoxins, and virotoxins can potentially affect all cells, however, the liver and kidneys are particularly vulnerable and often bear the brunt of their harmful effects. These organs are primary targets for toxicity, and exposure to Amanita parcivolvata can cause severe damage to their cellular integrity and function.
Furthermore, it is important to note that these toxins are heat-stable, meaning they can withstand high temperatures and are not easily eliminated through cooking methods such as grilling, boiling, frying, or steaming. This makes these toxins even more dangerous as cooking Amanita parcivolvata or similar mushrooms will not neutralize or remove the toxic compounds present within them.
Poisoning following Amanita parcivolvata ingestion typically occurs in three stages: 8 to 12 hours, 12 to 48 hours, and 72 hours after ingestion. In the first stage, gastrointestinal symptoms such as nausea, vomiting, abdominal pain, diarrhea, and vertigo are prominent. The second stage brings temporary relief from these symptoms, which can give the affected individual a false sense of safety. However, during this stage, insidious liver and kidney failure may begin. The third stage is marked by liver failure-induced coagulopathy (bleeding from the nose, vomiting of blood, blood in urine, bloody stools) and encephalopathy (muscle twitching, altered mental state, seizures, coma). Without prompt and proper medical care, death usually occurs during the third stage.
No specific antidote exists for Amanita poisoning, resulting in limited treatment options. Medical intervention primarily revolves around supportive measures and, if feasible, gastrointestinal decontamination. Given the lack of a specific antidote, it is crucial for individuals to be able to correctly identify Amanita parcivolvata and other Amanitas and to avoid them in order to prevent accidental poisoning.[v]
[i] McKnight, K. H., & McKnight, V. B. (1998). Flimsy Veil: Amanita parcivolvata. In A Field Guide to Mushrooms, North America (pp. 229-230). Houghton Mifflin.
[ii] Kuo, M. (2013, May). Amanita parcivolvata.
[iii] D. Arora (1986) Amanita caesarea group In Mushrooms Demystified: A Comprehensive Guide to the Fleshy Fungi, (p. 284) Ten Speed Press, Berkeley
[iv] Lincoff, G. (1981). False Caesar’s Mushroom: Amanita parcivolvata. In National Audubon Society Field Guide to North American mushrooms (pp. 542-543) Knopf.