Edible Mushrooms in my Worm Bin

Every single time Bagasse Mushrooms appear in my compost I am amazed. Mainly because these mushrooms are considered to be gourmet edible mushrooms, fetching high prices at markets worldwide, yet they have decided to volunteer in no less than 3 of my compost systems! Before these mushrooms, aka Paddy Straw Mushrooms (Volvariella volvacea), began appearing in my compost, I had never intentionally cultivated them; I have never introduced their spawn nor their spores to the land that I am stewarding. I have never even bought this species of mushroom from the market; so no parts of this species – neither tissue nor spores – have ever intentionally ended up in my compost after having been on my kitchen’s cutting board! And yet they have found their way to my compost systems. I suspect the wind has brought in their spores.

Bagasse Mushroom growing in a raised bed keyhole composting chute under fruiting tomato plants by Chase | Tropical Fungi Academy

Different mushroom species frequently pop up in my compost, most commonly different varieties of Inky Caps. Yet this mushroom species, no doubt due to its size, always elicits the “WOW factor” from myself & my roommates. Speaking of roommates, I can’t help but wonder if they are slicing-&-dicing Bagasse Mushrooms in the kitchen behind my back & surreptitiously sneaking pieces into our compost pails (they insist they are not though).

Bagasse Mushroom growing in compost tumbler by Chase | Tropical Fungi Academy

The Bagasse Mushroom is a hot weather loving mushroom that is widely cultivated in the tropics. Due to its extremely short shelf life, fresh specimens can only be purchased in locations very close to where they are grown. Most people around the world who eat these mushrooms get them preserved in tin cans labeled “Straw Mushrooms” from grocery stores. They are most typically eaten in soups & stir fries & are prized for their delightful aroma & umami flavor.

Bagasse Mushrooms growing in worm compost bin. Note the compost worm crawling in between them! By Chase | Tropical Fungi Academy

Distinguishing features of Bagasse Mushrooms are their compost habitat, a prominent & thick, sack-like egg at the base of the stipe, lack of a ring or skirt on the stipe, & pinkish brown to salmon-colored spores (as seen on the spore-dusted on the caps in the photo above).

Properly identifying mushrooms takes a few steps. Oftentimes it is difficult – if not impossible – to identify a mushroom just by looking at its top surface alone.

It is critical to also look underneath the mushroom to see what kind of fertile surface type it has. Different species of fungi can sometimes look very similar from above, but actually have vastly different kinds of fertile surfaces below. For example, with the classic cap-and-stem mushroom the fertile surface is located on the bottom side of the cap. There you will see the fertile surface on which the mushrooms spore’s (like plant seeds) are formed.

There are 3 different shapes of fertile surface types that you will most often find under the cap:

Gills look like pages in a book.
Pores look like a bunch of small – sometimes very tiny – holes.
Teeth look like elongated, cone-shaped spines.
[…and some mushrooms have veins underneath.]

hymenophore types

Sometimes when identifying, we only want to know what type of fertile surface a mushroom has. To do this we actually do not need to pick it from the earth – or maybe the the mushroom doesn’t want to be picked! Perhaps it is still too young & we want it to complete its lifecycle by maturing & releasing its spores yet we still want to know what kind of mushroom it is. In this case, we can use a dental mirror to see what kind of fertile surface the mushroom has to help us with identification.

It’s easy. What we do is simply hold the dental mirror against the ground underneath the mushroom’s cap, & then angle the mirror towards our eyes so that we can see if the mushroom has gills, pores, or teeth. This step can either get us closer to identifying a mushroom to species or can sometimes even give us a definitive answer as to what the mushroom is.

Photo by Jason Youth | CC0 public domain | iNaturalist

Always be sure to see what kind of fertile surface the mushroom has. And if getting help from others by sending them your photographs of the mushroom, be sure to always include a photo of the fertile surface in addition to the top surface.

If you want to learn more about mushroom ID, then please join us for our next mushroom identification class by clicking here.