Friday, September 4, 2015

Identifying the Most Common Poisonous Mushroom: Chlorophyllum molybdites (the Green-Spored Lepiota)

There is one mushroom which I get shown pictures of, and asked to identify, more than any other. It seems to be the most commonly encountered, or at least most commonly noticed mushroom in any region of the U.S. that I have lived.

Many times the request for information also comes with something along the lines of "it looks like it would be tasty!" And, in fact, this large, pristine, ubiquitous, and frequently abundant mushroom does look like it would be a great meal. . .

But looks are frequently deceiving.

Chlorophyllum molybdites (commonly know as the Green-Spored Lepiota or the Green-Spored Parasol) is the cause of the most wild mushroom poisonings in the United States. The mushroom looks good, smells good, and apparently tastes good (since people consume entire meals), but only a little bit can make an adult violently ill. Symptoms include the usual gambit of diarrhea (can be bloody), vomiting, and severe stomach pain, and can last for more than a day.

Though not generally considered deadly, the very young and the very old can become dangerously, and perhaps fatally, ill if not taken to a hospital. Even healthy adults can experience dangerous levels of dehydration, and require hospitalization. There are reports of this mushroom being fatal to dogs, so I would recommend stamping it out of your yard if you have children or pets. 

Identification and Habitat

Very young Chlorophyllum molybditess are sort of like scaly golfballs on stalks.


These stately mushrooms start out as round balls on stalks, they expand to typical mushroom shape: medium to extra-large size. (Caps 2 inches to 10 or even 12 inches across). I would say they are most often 4 to 6 inches.

The cap is white, often creamy on the edges, and features tan scales and/or patches. The stem is relatively slender, and has areas of white and beige/tan. There is a ring around the stalk. The gills are white or cream when very young, and become green or greenish grey as the mushroom ages. (More on this later).


Sometimes the young mushrooms grow elongated. When they look like this, they can be confused with
edible shaggy mane mushrooms. Learn more below in the "confusion with other species" section.

An arc of Chlorophyllum molybdites.
My phone didn't pick up the scales at this distance,
but each mushroom had them. 
I most frequently encounter Chlorophyllum molybdites in the grass, especially lawns and parks after watering. However, I have also found them along pathways and frequently in wood chips.

In New Jersey, this mushroom was more likely to grow alone, or in small, scattered groups, and to grow very large (8" or more across).

In Texas however, the mushrooms are generally smaller (4"-6" at full size), but to grow in larger clusters, arcs, fairy rings, or groups.

Chlorophyllum molybdites can grow very large - I wear a size 10 shoe, and my foot is dwarfed by these.
These are not the largest I've seen. 
Though they were once considered more of a Southern mushroom, climate change and/or other factors seem to have increased the range considerably. I've encountered this mushroom as far north as Ithaca, NY, and it's very abundant here in Texas. I would doubt there is a continental state in the country which can be entirely free of them.


Season
Chlorophyllum molybdites can appear from spring to fall, but is most often seen in when the spring gets warm,  (May in most parts of the US, and April in the South) through the warmer months of fall (September in much of the country, October and into November in the South and Southwest).
Of course, these are rough estimates. The mushroom can grow whenever it's warm enough for it, and that can vary from year to year. It is not a mushroom you will see while there are frosts, however. 

This park was completely filled with huge clusters of Chlorophyllum molybdites

Confusion with Other Species.
I think the main reason Chlorophyllum molybdites is frequently eaten is simply it's abundance, and the fact that it's so easy to spot. The fact that it looks and smells good doesn't hurt either. It's also possible that the fact that it forms in fairy rings may confuse people, as the so-called "Fairy Ring Mushroom" (Marasmius Oreades) is edible. Be warned: many mushrooms form fairy rings. Deadly Gallerina varieties can grow from buried wood, looking like small fairy rings. 

However, Chlorophyllum molybdites also can resemble several edible mushrooms: the Parasol Mushroom (Macrolepiota procera),  Reddening Lepiota (Leucoagaricus americanus), and the Shaggy Parasol (Chlorophyllum rhacodes). NONE of these three mushrooms is a beginner (or even novice) mushroom! 

I honestly believe that the Parasol, Shaggy Parasol , and Reddening Lepiota should be hunted by fairly experienced mushroom hunters ONLY! Chlorophyllum molybdites is not the only mushroom which resembles these three, and getting sick is not the worst thing that can happen from mis-identification. Amanita thiersii is a potentially DEADLY mushroom which can be confused with any of these (especially the Parasol). Amanita thiersii will also have white spore prints, like these 3.

Young Chlorophyllum molybdites can also be mistaken for the edible shaggy mane mushrooms, Coprinus comatus.

At this age, Chlorophyllum molybdites can resemble shaggy manes,
especially in California where shaggy mane have a tan hue.
What bothers me about the shaggy mane, is that many books call it "fool proof" to ID. There are no foolproof mushrooms. The closest to foolproof would be the chicken of the woods, or the black trumpet, and I have pictures of mushrooms you could confuse with those as well. Shaggy manes are very easy to ID when they are decaying into black ooze, but they aren't edible at that point. When they are edible, they can very closely resemble a young Chlorophyllum molybdites, especially on the west coast/California, where the "shag" of shaggy mane frequently takes on a brown or tannish hue. 

Here's how to tell them apart: young Cholorophyllum molybdites has tough "scales", which will feel rubbery and not push back easily. If you do try to push them back (think like brushing fur backwards), they will not yield or they will break off. 

In contrast, the shaggy mane "shags" are soft and floppy. They will easily bend backwards when you brush them back. 

Also young Cholorophyllum molybdites will often (but not always) be found with older, more mature and "mushroom shaped" mushrooms. Do not eat any potential "shaggy manes" you find growing with mature Cholorophyllum molybdites unless you are experienced. 



Positive Identification of Chlorophyllum molybdites 

Fortunately, Chlorophyllum molybdites has one hard and fast way to identify it--if you have the patience! All mushrooms reproduce with spores, tiny, invisible to the naked eye, "seeds" which are stored in the gills of gilled mushrooms.  All 4 of the similar looking mushrooms (Parasol, Reddening Lepiota, Shaggy Parasol and Amanita thiersii) have white spores, but the spores of Chlorophyllum molybdites are a light sage green. 

The gills of this mushroom are just starting to stain greenish grey.
However a spore print is a better way to make sure.
These green spores are the reason the gills of older mushrooms turn green or greenish grey--they get stained with the falling spores. However, you can also use this to identify young Chlorophyllum molybdites--but you have to do a spore print. 

This sage green spore print  confirms the mushroom as Chlorophyllum molybdites

I really need to do a post all about spore prints, and I will soon. But basically, the easiest way to do a spore print is to have a piece of white paper and a piece of dark paper. (black construction paper is best, but even a brown grocery bag will do in a pinch). 

Harvest a wild mushroom, and cut the cap off from the stem. Place the cap gill-side down (or pore-side down in the case of boletes), so that half the cap rests on the white paper, and half rests on the dark paper. Cover the mushroom and paper with an upside-down bowl and let rest overnight. 

The next morning carefully remove the bowl and the mushroom cap. Assuming you harvested a mature mushroom (young mushrooms don't spore, and old mushrooms have already spored), the spores will have fallen out onto the paper, leaving an impression, called a "spore print". 

Note: for safety's sake, do NOT leave a mushroom that is being spore printed out where it might be consumed by a curious child or pet. Unknown mushrooms can be fatal. Even mushrooms known to be edible by humans can kill a dog or cat, and can still make a child ill if consumed raw. 

Returning to the same mushroom patch 2 days later shows how
the gills are now green-grey. Also, the caps are now nearly flat--
having spread out to release their spores.
In this case, if your mushroom leaves a light sage-green spore print, you have positively identified  Chlorophyllum molybdites. All of the other large mushrooms which resemble it will have white spore prints.

Every time you positively ID a mushroom, you gain in knowledge, skill and experience--becoming a better mushroom hunter, and coming one step closer to being able to safely ID the intermediate and advanced mushrooms (and eventually expert mushrooms--not that I'm there yet!).

Important: a white spore print indicates the mushroom is not Chlorophyllum molybdites. It does NOT make the mushroom safe to eat. Amanita thiersii is potentially DEADLY and also has a white spore print. Other potentially deadly Amanitas might also be confused for the Parasol and company. 

Is Your Yard Overrun with Chlorophyllum molybdites?

Given the potential danger this mushroom can pose to children and pets, I would strongly recommend stomping it out of your yard if there is any danger of it being encountered by either. Chlorophyll molybdites will come up in the same general area, time after time, and generally starts to grow overnight, so doing a cursory sweep for young mushrooms in the area in the morning before you go to work should suffice. 

Stomping out the mushrooms won't "kill" them, and it won't prevent them from coming back, it only guards against accidental ingestion. The actual living organism is in the ground, the mushrooms are actually it's fruit, and killing them does no more damage than picking an apple, or getting a haircut. 

If you want to prevent the mushroom from growing I would suggest seeing if you can change your watering schedule. Here in Texas, I've only ever seen the mushroom grow when there were deep soaking rains, or after heavy overnight watering. Even back in NJ,  I mostly saw if in well-watered yards and landscaped areas after watering (or during spring rains, which you can't control). 

Even morning stomping and changing your watering routine won't completely rid your yard of Chlorophyll molybdites, as this photo shows. Here, all-day heavy rains prompted growth in the afternoon and evening, instead of the early morning as per usual. 

Assuming your local ordinances allow it, consider switching from overnight watering to early morning watering, and/or instead of heavily watering 2-3 times a week, do a lighter watering every day.  Of course, please follow best water conservation for your area, and only try these steps if you are not in a water-restricted region. 

I don't suggest chemical fungal remediation. Saprobes (decomposer) mushrooms are notoriously hard to eradicate. Their presence indicates that you have something delicious in your yard (perhaps a buried log or tree stump) and even if you kill these mushrooms, others will be drawn to the feast and grow in their place.

6 comments:

  1. Glad to find this article! I found some chlorophyllum molybdites in a neighbor's yard and we were both wondering if it's edible or not. Will print out your article and show my neighbor. Thanks you!

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    1. Great! I am so so glad you didn't try it. My coworker said she was taking the bus one day, after talking to me about them, and saw a guy with 3 large, freshly picked ones. She tried to warn him but he just shrugged her off.

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  2. This is a great article about mushroom identification.

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    1. Thanks Richard, I have a new post up, about identifying the edible ringless honey mushroom, you should check it out!

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  3. Thank you very much. I got some mushrooms and I thought they could be Psilocibes cubensis.

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    1. Hi, I'm sorry but I make it a policy not to ID fungi which could be used for illegal purposes. In general, those mushrooms fall under the category of "little brown" or "little white" mushrooms, all of which are hard to get a positive identification on, and have many dangerous and deadly look-alikes. They are best left alone.

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