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The Private Eye Field Report Private Eye Field Adventures: Of Osage Oranges and Earthstars

      We took off on a blustery late November day from the office to visit a new hiking/walking path that wends its way across a hillside beside the wild and scenic Klickitat river, a 3-minute drive from The Private Eye HQ.

Osage orange fruitOsage orange trees stood, sentinel anomalies, in two unkempt rows, elbowing each other as the westerlies made them dance. Their exotic offspring, strangely spring-green, whorled and dimpled, hung suspended in high branches or lay shucked in puddles downhill of the trees in varying states of decomposition. Osage orange was the first tree Lewis and Clark sent back East from the early stages of their expedition; settlers had expanded the tree's territory westward by planting it in shelterbelts.Klickitat River with inlet and oak trees

     Mostly, though, umber-leaved oaks and ponderosa pines lined our path and dotted the rounded hillsides nearby. The river, as Kerry said, took on a molten metallic quality in the flat-angled light of approaching winter. David identified the nearly invisible birds exploding and resettling in the boughs of the trees above us as bushtits. We were drawn toward the fenceline separating the mantle of the hill from its basalt cliffs that dropped down to the water and a small inlet, now deprived of its early-season creek source, but still hosting a bevy of waterfowl.

      As we walked along the meadow-topped hill, I stopped to pick up what looked like a large chestnut that had split open, and whose meat appeared to be shrunken (though smooth) and covered with mold or algae—it appeared shrunken as it didn't fill out its surrounding leathery, star-shaped shell. I thought it was curious and pointed it out to David, Kerry and Francis. A few steps later, I bent down to pick up a similar “chestnut”, only this one's shell had not only split open, but had curled back, exposing a cracking, leathery interior. The inverted corona formed a sort of pedestal supporting a flattened cushion, whose texture was quite different. This was no ordinary chestnut, and there wasn't a chestnut tree in sight. We were puzzled, but left the two specimens, evidently in varying states of maturity, on the fence posts and continued on our walk. Private Eye employee inspecting earthstar fungus using jeweler's loupe

      Curiosity got the better of us on the way back, however, and we scoured the ground for more clues. We found several more of these odd objects, most inverted like the second one we'd found. As we looked closely in the disturbed soil (disturbed, we imagined, from the recent digging out of the walking path), we saw divots where more of these fungi– as we now assumed — were peeking out. Some were still enclosed in their shell and mostly underground; some had erupted and were sitting atop inverted crowns above ground. What a sight! They suddenly seemed to be everywhere! We had discovered a mushroom none of us had ever seen before! We inspected the soil from which they were emerging as well as the surroundings — they were more or less exposed (not under tree canopy), but near large oaks. The ground was damp from recent rains, but it didn't appear that these mushrooms had all emerged recently; they looked as though they had painstakingly shrugged their way through the earth's epidermis over days; perhaps weeks, perhaps months. We collected several more specimens in varying stages of inversion and decomposition. Earthstar fungusWe used our Private Eye loupes (on loupe-leashes around our necks, naturally!) to inspect the objects more closely. The sac in the middle was kid-leather smooth containing an extremely fine, powdery substance, which in some specimens had turned a deep, rich brown. In fact, it resembled cocoa powder. Kerry exclaimed that it reminded her of puffball mushrooms. We mused and pondered a bit more, resolving to solve the mystery when we got back to work.

      My fingers became numb carrying my small stash of these odd, damp specimens back to the car through the wind, taking care not to crush them, though they looked fairly tough.

Inspecting earthstar fungi with jeweler's loupes in Private Eye lab with jeweler's loupes Upon returning to the office, we dug right into “Mushrooms of North America”, a field guide to fungi by Orson K. Miller, Jr., and were able to narrow down our specimens by closely observing their structures using our loupes. We then compared the structures we saw with those in an illustrated glossary in the back of the book. We looked up the options that seemed most similar on the internet, and were rewarded with excellent pictures and detailed descriptions on a site called We first ran across something that looked familiar called Geastrum coronatum *—Earthstars! How appropriate. They are in the Lycoperdales family, closely related to…the puffballs! So when Kerry said that these strange items reminded her of puffballs…she was headed down the right path. And in our case, a crowned earthstar, which accounted for the rays that radiated outward from the central “fruit”.

      The habitat description didn't match ours exactly. True, the earthstars were “gregarious”, but here, at least, they weren't growing under conifers or cypress; only the pines and oaks. They did seem to fit the “fruiting from after the fall rains to late winter” bit.

      I was delighted to stumble across a whole slew of new vocabulary in poring over the description: the central nugget of the fruiting body, or sporocarp (spore sac), was subglobose (not quite round), and the mushrooms themselves, hypogeous (growing and ripening underground), then erumpent (breaking through the surface)... a whole polysyllabic world of strange colors, textures, structures and consonants had opened before us! (For more tongue-twisting mycological morphology, see the links below.) We confirmed that the cocoa puff gleba (the sporemass, or mycelium, inside a puffball) was indeed supposed to be dark brown at maturity. As we read on, however, we found that our geastrum closely resembles another earthstar, astraeus hygrometricus**. After following the web trail to astraeus, we discovered that it was likely our suspect! Researching earthstar fungi in Private Eye lab with jeweler's loupes

Perhaps most exciting to us is that the role of these earthstars in nature is not known for certain; some experts think earthstars form mycorrhizae (fungi that form symbiotic relationships with roots of more developed plants). To figure out what a foreign, unfamiliar object in our environment was we'd gotten on the right track using the power of loupe + analogy-provoking questions. We'd put on our Private Eye hats and solved one mystery only to uncover a new one—so these strange objects are Earthstars, but what is an Earthstar, really, and what role does it play? The puzzler remains to be solved...


Do you have any Private Eye adventures—fungal or just plain fun—you'd like to share with us?  We welcome field report submissions about what you've discovered using The Private Eye—one little paragraph or a whole essay!

Astraeus hygrometricus : earthstar fungus                       

*See the “Naming by Analogy” section on p.143 in The Private Eye guide!

**There is some scientific debate as to the morphology of and relationship between geasters and astraeus--see Tom Volk's Fungus page, below. 

Osage orange surface seen through a Private Eye jeweler's loupe

After researching the osage orange (maclura pomifera), I found that barbed wire had been designed to mimic the thorny green hedges of osage, which settlers on the Great Plains planted close together and pruned to be, ideally, “horse-high, bull-strong and hog-tight”. Green branches can also be planted in the ground and turned into a living hedge. The tree is named after the Osage tribe of Western Missouri through Northwestern Arkansas, who prized the wood of the tree for making bows (another name for the tree is "bodark", an adaptation of the French "bois d'arc" meaning bow wood). The wood is also highly resistant to fungus, which makes it very useful for fence posts. The dried wood, when burned, has some of the highest heat output of any native hardwoods. It turns out that osage orange trees are in the same family as mulberry trees, and if you were to look at a mulberry with a loupe, you'd see that its texture is, in micro scale, very similar to that of the convoluted surface of the osage orange.

For more fascinating facts and information about osage orange trees, see:

Plants of the Lewis & Clark Expedition (H. Wayne Phillips, 2003), Mountain Press Publishing.

Or more on earthstars:

Astraeus hygrometricus: sporocarp

Tom Volk's Fungus of the Month for December 2003




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