Invisible Nature: Star of the Dunes

Coastal dunes set the stage for a surprisingly valuable partnership between a fungus and a tree.

Alongside the seagulls and shells on Massachusetts’s Cape Cod, observant beach-goers are occasionally lucky enough to stumble upon an earthstar (Astraeus sp.), a strange fungus that makes its living in New England’s coastal dunes. Above the sand, the fungus, sometimes called a “water-bearer” or “barometer” earthstar, is represented solely by its fruiting body, the structure responsible for reproduction. This structure normally remains shriveled into a tight ball. But when it gets wet, the earthstar’s “petals” unfurl to reveal a spore-filled puffball. Some species of earthstar can open and close many times over the course of their lifespan.

As fascinating as these above-ground events may be, they are only part of the earthstar’s complex life history. Underground, the fungus forms a partnership with a plant—in many cases the region’s ubiquitous pitch pine (Pinus rigida). Through specialized structures known as mycorrhizae that connect the two organisms, the earthstar and the plant exchange water and nutrients for carbohydrates. This trade of goods allows both partners to survive in this austere environment, and, in turn, helps to stabilize the dunes that coastal communities and countless organisms rely upon.

Annette Heist, Ruth Lichtman, and Flora Lichtman

Annette Heist is a science writer, radio producer, and a registered nurse working in behavioral health. Ruth Lichtman is a multi-disciplinary visual artist and filmmaker whose work has been featured on The New York Times, The Atlantic, Aeon, and The Huffington Post. Flora Lichtman is a science journalist who has worked for “Bill Nye Saves the World” on Netflix, The New York Times, and Science Friday. She hosts a podcast called Every Little Thing.

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