Story behind the art of Janet Goltz

Curious Allies: Mutualism in Fungi, Parasites, and Carnivores

The Fifth New York Botanical Garden Triennial

Hygroscopic Earthstar

Astraeus hygrometricus

In September 2010, I took a Minnesota School of Botanical Art watercolor class on painting mushrooms. Soon after my husband, Howard, and I became members of the Minnesota Mycological Society and the North American Mycological Association (NAMA). This opened the incredible world of mushrooms to us. Howard has since photographed thousands of mushrooms and accumulated many forager identification books. As we participated in group forays, my fascination and amazement with fungi grew. In 2017, in the Chequamegon National Forest around Cable, Wisconsin, we participated with other NAMA foragers in collecting and identifying over 500 unique mushroom species in three days. You can imagine rows and rows of tables where these mushrooms were displayed. In the Colorado Rockies, the 2021 NAMA foray found amazing numbers of the choice edible “Colorado red” variety of the porcini mushroom, Boletus rubriceps. I found an awesome, four-pound, pristine specimen that was over a foot tall and wide, looking like a giant button mushroom.

Of all the mushroom shapes there are, there is one, Astraeus hygrometricus, that especially captured my interest. Commonly known as the hygroscopic earthstar, the barometer earthstar, or the false earthstar, this is a species of fungus in the family Diplocystaceae. The mature mushroom looks like a small puffball balanced on top of star shaped legs. This ball rises on these “star legs” in humid or wet conditions. I finally found a small group of them in General Andrew’s State Park, in northern Minnesota, just where it should be, in a pine forest on sandy disturbed soil. Because the soil and weather were humid, this group was perfect, plump and erect, each standing on triangular legs, arranged around a central fruiting “ball,” looking like a child’s toy. The ray-like legs push down, allowing the central spore producing sac to rise above the forest duff and litter, where wind and rain puncture the sac and release the spores upward. The fruiting body decomposes after all the spores are released. 

This mushroom is hygroscopic (thus its name, meaning it absorbs moisture from the air) and ectomycorrhizal, having a symbiotic relationship, wherein the surrounding trees get help from the fungus though the entangled mushroom mycelium and tree roots, with the mushroom providing the tree with nutrients and defense against soil pathogens and nematodes. In turn, the fungus receives nutritional carbohydrates from the photosynthetic processes of its partner trees.

To learn more about mushrooms and their important relationship to our world, I highly recommend watching Fantastic Fungi, a 2019 American documentary film directed by Louie Schwartzberg. The film combines time-lapse cinematography and computer-generated imagery in an overview of the biology, environmental roles, and various uses of fungi. It includes interviews with Paul Stamets and Michael Pollan, and is narrated by Brie Larson.

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