Genus Amanita, Section Phalloideae
The Deadly Amanitas: The Destroying Angels and the Death Cap
The members of the Phalloideae are quite distinctive. They have a combination of features – a ring on the stem and a persistent cup at the base of the stem – that no other gilled mushroom outside Amanita has. Hopefully this combination of features was used to teach you about them first thing when you started to learn about identifying mushrooms so it is burned into your brain. If not, burn it in now! The only other section of Amanita to have both a cup and ring are the Caesareae, which are more warmly colored (though some west coast Caesareae that are collected for eating can get a bit brownish olivy, like the death cap).
The Death Cap
The death cap (Amanita phalloides) has an olive-brown cap and the archetypal cup and ring. It also sometimes has the odor more commonly associated with various Lepidella species, a sickly-sweet smell that is sometimes compared to rotten ham. It grows mostly with oaks but also with pines.
The Destroying Angels
Destroying Angels are a group of completely white Amanitas with the aforementioned ring and cup. There are quite a few of them, and it’s not clear at this point how to tell some of them apart without sequencing their DNA.
The Names of Destroying Angel: a cautionary taleWhen Europeans first came to this continent, they named our eastern destroying angel(s) with the name of the default European one, Amanita verna. As with so many other mushrooms, they thought that if it looks the same as the European version, it must be the same. This persisted until the mid twentieth century, and if you find older American field guides, they will use this name.
In the meantime, George Atkinson had named a destroying angel that only had two spores per basidium. He called this mushroom Amanita bisporigera. It grew at a different season than our more robust destroying angels, and it was smaller and more gracile than them.
But around that time, more people started checking the spores of our default destroying angel and found that they were (almost) round, whereas the spores of Amanita verna are elliptical. This was taken as an indication that we had two distinct species on our hands, and mycologists combed the literature for a destroying angel that had round spores. This was found in Amanita virosa, a mushroom named by the Swiss mycologist Secretan in the early 1800s. This is the name that will (still) be in most American field guides.
But mycologists checked up again — more quickly this time –and found problems with the name virosa. Quickly put, the real Amanita virosa has a distinctly pointy cap and smells and strongly of radishes. In fact, its name virosa refers to the strength of the smell rather than the strength of its poison. It is quite shaggy, and it prefers cooler weather – up in the mountains (Switzerland!) and in Scandinavia. So it is not our common eastern destroying angel, either.
During the same period of time, mycologists were also starting to be more and more convinced that the common eastern destroying angel and the more delicate one were the same thing. Experienced people were seeing them come up in the same place (and only in those places) at different times of the year. Other people would find mixtures of both sizes/statures growing together. There are other cases turned up of other mushroom species that people had declared on the basis of being the same as an existing one but differing in the number of spores per basidia. More and more of these turned out to be invalid; it seemed clearer and clearer that some fungi just sometimes produce four spores and one time and two spores at another.
So the picture that emerged during the 1990s was that (a) the common destroying angel had no proper scientific name and (b) this was actually the same thing as the smaller, more delicate destroying angel that was named by Atkinson back in the day. Since the smaller one was properly named, and the two are the same thing, this name was extended to the larger, more common version and they were both known as bisporigera. The taxonomy was simplified, everything made sense, and people rejoiced throughout the land!
Alas, it was not to be. When our eastern destroying angels were subjected to DNA testing, we turned out to have no less than five species of large destroying angel, and these are all distinct from A. bisporigera. This species is indeed truly smaller and more gracile than its brethren, and it’s the only one that has two-spored basidia (justas George Atkinson originally claimed).
The categorization and identification of the larger ones is a big mess. There are several names that have been in use for these mushrooms, but it’s unclear how to tell them apart or even if they were originally described in a way that reflects the actual boundaries between the species. There are some classic tests, like for example seeing whether the cap surface turns yellow in reaction to KOH. But at this point, we have no idea whether this test gives any information about species because the results haven’t been cross-checked with other ways of determining species.
This leaves us in the uncomfortable position of knowing that all the scientific names we have for our large eastern destroying angels are wrong (except for the white form of A. phalloides). Until this gets sorted out, I recommend just saying that they are destroying angels, and leaving out the scientific species names altogether.