The Urban Pantheist

One of my favorite habitats is also one of my favorite tags: the great indoors. It may be humanity’s most distinctive invention—millions of more or less fully enclosed climate-controlled spaces, all within a few degrees of temperature and humidity from one another. Human movement and commerce links these spaces to one another—second hand furniture harbors a population of bedbugs, spiders move into milk crates used to store books, a fruit fly hatches in your house from an egg laid on a banana in a warehouse 500 miles away.

Most of these creatures enjoy the same range of temperatures that we do. Many will leave the indoors during favorable weather only to have their descendants move back in when it becomes inclement again. Some of the great indoors is warmer and more humid than humans prefer—greenhouses, boiler rooms, pet stores, and others. Here there may be flies and cockroaches from the African tropics. There is even a tropical mushroom that likes the great indoors.

The yellow flowerpot mushroom Leucocoprinus birnbaumii* thrives in rich warm moist soil, a habitat that describes most potted plants kept indoors. The fungus can’t survive a freeze, so temperate dwellers like myself have to wait for our houseplants to surprise us, rather than finding them outdoors. Plant-fancier message boards are cluttered with panicked queries about this species, whether it is killing the ficus or poisoning the jalapeños in the pot. This fungus causes no harm to the plants it shares habitat with, and the mushroom wilts away in hours after appearing. It should not be considered a serendipitous source of food—the mushroom is known to be toxic and ingesting it results in digestive symptoms.

*“Birnbaum’s colorless poop eater"

You know, I said a little while ago that I should make a special website or other media project that collects all the mushrooms commonly found in human-impacted and human created ecosystems. Something like http://urbanmushrooms.com/ which, as it turns out, already exists. It's not perfect (found some obsolete synonyms in use there) but it is exactly what I was thinking of doing. Not that I can't do the same thing in my own style, but I thought you should know it's there.


So, speaking of which, here is a mushroom found only indoors--at least in temperate zones. This is a tropical species, Leucocoprinus birnbaumii which has found its way into the highly fragmented yet consistent ecosystem of greenhouses and house plants. This fruiting appeared in one of the planters in the Tropical Forest exhibit at Franklin Park Zoo (in a place not visible to the public nor accessible by the animals, in the giant anteater exhibit). A zookeeper friend (perhaps one seen here earlier, pointing her lips at a beetle grub) brought it to my attention, as I am becoming known as "the mushroom guy" around work.

As luck would have it, I had seen photos of the mushroom online the week before--a gardener found it in his potted pepper plant and was posting it concerned that it would harm his peppers or transfers poisons to them. (By the way, the answer is no to both. Mushrooms coming from the soil near a plant are almost always beneficial or neutral to the plant--parasites usually grow directly from the visible plant tissue. Poisonous mushrooms don't imbue their neighbors with poisonous essence--if anything, they are more likely to remove poisons from the nearby soil.)

This fascinating adaptation to the great indoors is paralleled by many small tropical animal species as well as tropical microbes. There are studies being done as we speak comparing the indoor wildlife of households in different parts of the world. I look forward to seeing the results of these studies--what do we all share, what's unique to one place or another. This mushroom is one of only two mushrooms I am aware of that is primarily found indoors, at least through much of its range.


A freshly emerged Leucocoprinus button. Common names for this mushroom boil down to some combination of "yellow," "potted plant," and "parasol."

This mushroom is dainty and beautiful, and resembles mushrooms in the Coprinus group, most of which are edible. This species is not edible to humans, causing some gastric distress. Its edibility to anteaters is not known to be, but fortunately they were growing out of his reach.